U.S. patent application number 15/374685 was filed with the patent office on 2017-06-15 for hand held appliance.
This patent application is currently assigned to Dyson Technology Limited. The applicant listed for this patent is Dyson Technology Limited. Invention is credited to Robert Mark Brett COULTON, James Richard Warren HEWITT, Pierpaolo LAVENI, Renzo RE.
Application Number | 20170164709 15/374685 |
Document ID | / |
Family ID | 55234642 |
Filed Date | 2017-06-15 |
United States Patent
Application |
20170164709 |
Kind Code |
A1 |
LAVENI; Pierpaolo ; et
al. |
June 15, 2017 |
HAND HELD APPLIANCE
Abstract
A hair care appliance that includes a body, a fluid flow path
extending from a fluid inlet into the appliance to a fluid outlet
from the body, a heater for heating fluid in the fluid flow path, a
pre-heater located upstream of the heater and a thermal safety
device positioned between the pre-heater and the heater. The
pre-heater may include a resistive element. The pre-heater may be
electrically connected to the heater via a heater circuit. The
thermal safety device may be electrically connected to the heater
via the heater circuit. When the appliance is activated, fluid may
flow from the fluid inlet through the pre-heater, past the thermal
safety device, through the heater and on to the fluid outlet. The
thermal safety device may extend orthogonal to a longitudinal axis
A-A of the body.
Inventors: |
LAVENI; Pierpaolo;
(Piacenza, IT) ; RE; Renzo; (Piacenza, IT)
; HEWITT; James Richard Warren; (Swindon, GB) ;
COULTON; Robert Mark Brett; (Bristol, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dyson Technology Limited |
Wiltshire |
|
GB |
|
|
Assignee: |
Dyson Technology Limited
Wiltshire
GB
|
Family ID: |
55234642 |
Appl. No.: |
15/374685 |
Filed: |
December 9, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A45D 20/12 20130101;
A45D 20/10 20130101 |
International
Class: |
A45D 20/10 20060101
A45D020/10; A45D 20/12 20060101 A45D020/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 2015 |
GB |
1521694.8 |
Claims
1. A hair care appliance comprising a body, a fluid flow path
extending from a fluid inlet into the appliance to a fluid outlet
from the body, a heater comprising a heater element for heating
fluid in the fluid flow path, a pre-heater located upstream of the
heater and a thermal safety device positioned between the
pre-heater and the heater and a wall extending around the periphery
of the heater element.
2. The appliance of claim 1, wherein the pre-heater comprises a
resistive element.
3. The appliance of claim 2, wherein, the pre-heater is
electrically connected to the heater via a heater circuit.
4. The appliance of claim 1, wherein the thermal safety device is
electrically connected to the heater via the heater circuit.
5. The appliance of claim 1, wherein when the appliance is
activated, fluid flows from the fluid inlet through the pre-heater,
past the thermal safety device, through the heater and on to the
fluid outlet.
6. The appliance of claim 1, wherein the body has a first end, a
second end and a longitudinal axis A-A extending from the first end
to the second end, wherein the fluid flow path extends along the
longitudinal axis A-A.
7. The appliance of claim 6, wherein the thermal safety device
extends orthogonal to the longitudinal axis A-A of the body.
8. The appliance of claim 6, wherein the pre-heater extends
orthogonal to the longitudinal axis A-A of the body.
9. The appliance of claim 6, wherein the pre-heater extends across
the length of the thermal safety device.
10. The appliance of claim 1, wherein the wall additionally extends
around the periphery of the pre-heater.
11. The appliance of claim 1, wherein the appliance is a hairdryer.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority of United Kingdom
Application No. 1521694.8, filed Dec. 9, 2015, the entire contents
of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to a handheld appliance and in
particular a hair care appliance such as a hairdryer.
BACKGROUND OF THE INVENTION
[0003] Generally, a motor and fan are provided which draw fluid
into a body; the fluid may be heated prior to exiting the body. The
motor is susceptible to damage from foreign objects such as dirt or
hair so conventionally a filter is provided at the fluid inlet to
the blower. The fan and heater require power in order to function
and this is provided via internal wiring from either a mains power
cable or batteries attached to the appliance.
[0004] Conventional hairdryers have control buttons which can
change one or more of the flow rate and the temperature of the
fluid that exits the hairdryer. However, if the flow rate is
increased there is usually a drop in the temperature of the fluid
that exits the hairdryer that can be perceived by the user.
[0005] The temperature of the fluid that exits the hairdryer is
also affected by other factors. There can be an electrical failure
of some sort; alternatively dust and dirt can be pulled into the
heater element and if this builds up it can burn and cause an
increase in the temperature of the fluid exiting the hairdryer.
Obviously, thermal protection is provided in the form of thermal
cut outs such as thermal fuses or bi-metallic strips to prevent an
excessive increase in temperature but such protection renders the
hairdryer inoperable either temporarily or permanently.
[0006] A bi-metallic strip is a temporary thermal cut out and is
only effective if it is positioned within the fluid flow path in
heated fluid. It is known to position such as safety device
downstream of the heater, such as is disclosed in Japanese Patent
Application 60-78826. One problem with this is that it causes the
length of the product to be increased in order to house the safety
device.
[0007] Other solutions have been to either place the safety device
within the windings of the heater, as is disclosed in Italian
Patent Number 255589 however this adds to the complexity of
manufacture of the heater or, to position the bi-metallic strip
radially external to the heater however, this requires the diameter
of the housing to be increased to accommodate the safety
device.
SUMMARY OF THE INVENTION
[0008] Aspects of the invention provide an alternative solution
that does not cause the size of the product to be increased and
does not require a local modification of the heater element
windings to accommodate the thermal safety device.
[0009] According to a first aspect, the invention provides a hair
care appliance comprising a body, a fluid flow path extending from
a fluid inlet into the appliance to a fluid outlet from the body, a
heater for heating fluid in the fluid flow path, a pre-heater
located upstream of the heater and a thermal safety device
positioned between the pre-heater and the heater.
[0010] The pre-heater mimics or simulates the temperature of the
heater for the bi-metallic strip. Thus, even though fluid that is
heated by the heater does not flow around and over the bi-metallic
strip, the bi-metallic strip experiences an imitation or simile of
the fluid heated by the heater by the pre-heater.
[0011] Preferably, the pre-heater comprises a resistive
element.
[0012] In a preferred embodiment, the pre-heater is electrically
connected to the heater via a heater circuit.
[0013] Preferably, the thermal safety device is electrically
connected to the heater via the heater circuit.
[0014] In one embodiment, the thermal safety device is positioned
before the heater within the heater circuit thus, if the thermal
safety device is activated, current does not reach the heater. The
thermal safety device is positioned between the heater and the
on/off switch.
[0015] The per-heater may also be located before the heater within
the heater circuit. It is preferred that the pre-heater is between
the thermal safety device and the heater. Thus, if there is a
blockage at the primary fluid inlet, the pre-heater being upstream
of the heater will respond to the reduced flow before the heater,
causing the thermal safety device to trip or activate before the
heater causes any significant rise in temperature within the
appliance.
[0016] In a preferred embodiment, when the appliance is activated,
fluid flows from the fluid inlet through the pre-heater, past the
thermal safety device, through the heater and on to the fluid
outlet. Thus, the pre-heater will respond to a reduced flow within
the primary fluid flow path before the heater, causing the thermal
safety device to trip or activate before the heater causes any
significant rise in temperature within the appliance.
[0017] Preferably, the body has a first end, a second end and a
longitudinal axis A-A extending from the first end to the second
end, wherein the fluid flow path extends along the longitudinal
axis A-A.
[0018] In a preferred embodiment, the thermal safety device extends
orthogonal to the longitudinal axis A-A of the body. This is
advantageous as it maximises the exposure of the thermal safety
device to the fluid flowing through the primary fluid flow path.
Were the thermal safety device positioned along the primary fluid
flow path a small volume of the fluid flowing would pass near the
thermal safety device, by positioning it across the flow a larger
arc of the fluid flowing passes directly over the thermal safety
device.
[0019] Preferably, the pre-heater extends orthogonal to the
longitudinal axis A-A of the body.
[0020] In a preferred embodiment, the pre-heater extends across the
length of the thermal safety device. This maximises the
effectiveness of this safety feature.
[0021] Preferably, the heater comprises a heater element and a wall
extending around the periphery of the heater element .
[0022] In a preferred embodiment, the wall additionally extends
around the periphery of the pre-heater.
[0023] Preferably, the appliance is a hairdryer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The invention will now be described, by way of example only,
with reference to the accompanying drawings, in which:
[0025] FIG. 1 shows a hairdryer in which a thermistor according to
the invention may be used;
[0026] FIG. 2 shows a cross section through the hairdryer of FIG.
1;
[0027] FIG. 3 shows an isometric view of a heater assembly
according to the invention;
[0028] FIG. 4a shows a further isometric view of the heater
assembly of FIG. 3;
[0029] FIG. 4b shows an exploded isometric view of the pre-heater
of FIG. 4a;
[0030] FIG. 5 shows a top view of the heater assembly of FIG. 3;
and
[0031] FIG. 6 shows schematically parts of the heater circuit.
DETAILED DESCRIPTION OF THE INVENTION
[0032] FIGS. 1 and 2 show an example of hairdryer 10 with a handle
20 and a body 30 suitable for use with a thermistor according to
the invention. The handle has a first end 22 which is connected to
the body 30 and a second end 24 distal from the body 30 and which
includes a primary fluid inlet 40. Power is supplied to the
hairdryer 10 via a cable 50. At a distal end of the cable 50 from
the hairdryer 10 a plug (not shown) is provided, the plug may
provide electrical connection to mains power or to a battery pack
for example.
[0033] The handle 20 has an outer wall 200 which extends from the
body 30 towards a distal end 24 of the handle. At the distal end 24
of the handle an end wall 210 extends across the outer wall 200.
The cable 50 enters the hairdryer through this end wall 210. The
primary fluid inlet 40 in the handle 20 includes first apertures
that extend around and along 42 the outer wall 200 of the handle in
a series of rows and/or columns that extend from the distal end 24
of the handle 20 and second apertures that extend across 46 and
through the end wall 210 of the handle 20. The first and second
apertures form an initial filter for the primary fluid inlet and
help to prevent hair and other foreign objects from entering.
Ideally, a second finer filter 44 is provided. The cable 50 is
located approximately in the middle of the end wall 210 so extends
from the centre of the handle 20. The handle 20 has a longitudinal
axis X-X along which the outer wall 200 extends from the body 30
towards the distal end 24.
[0034] Upstream of the primary fluid inlet 40, a fan unit 70 is
provided. The fan unit 70 includes a fan and a motor. The fan unit
70 draws fluid through the primary fluid inlet 40 towards the body
30 through a primary fluid flow path 400 that extends from the
primary fluid inlet 40 and into the body 30 where the handle 20 and
the body 30 are joined 90. The body 30 has a first end 32 and a
second end 34, the primary fluid flow path 400 continues through
the body 30 towards the second end 34 of the body, around a heater
80 and to a primary fluid outlet 440 where fluid that is drawn in
by the fan unit exits the primary fluid flow path 400. The primary
fluid flow path 400 is non linear and flows through the handle 20
in a first direction and through the body 30 in a second direction
which is orthogonal to the first direction.
[0035] The body 30 includes an outer wall 360 and an inner duct
310. The primary fluid flow path 400 extends along the body from
the junction 90 of the handle 20 and the body 30 between the outer
wall 360 and the inner duct 310 towards the primary fluid outlet
440 at the second end 34 of the body 30.
[0036] An inner wall 260 extends within the outer wall 360. The
inner wall 260 at least partially defines the primary fluid outlet
440 and extends from the second end 34 of the body 30 between the
inner duct 310 and the outer wall 360.
[0037] Another fluid flow path is provided within the body; this
flow is not directly processed by the fan unit or the heater but is
drawn into the hairdryer by the action of the fan unit producing
the primary flow through the hairdryer. This fluid flow is
entrained into the hairdryer by the fluid flowing through the
primary fluid flow path 400.
[0038] The first end 32 of the body includes a fluid inlet 320 and
the second end 34 of the body includes a fluid outlet 340. Both the
fluid inlet 320 and the fluid outlet 340 are at least partially
defined by the inner duct 310 which is an inner wall of the body 30
and extends within and along the body. A fluid flow path 300
extends within the inner duct 310 from the fluid inlet 320 to the
fluid outlet 340. At the first end 32 of the body 30, a side wall
350 extends between the outer wall 360 and the inner duct 310. This
side wall 350 at least partially defines the fluid inlet 320. The
primary fluid outlet 440 is annular and surrounds the fluid flow
path.
[0039] A printed circuit board (PCB) 75 including the control
electronics for the hairdryer is located in the body 30 near the
side wall 350 and fluid inlet 320. The PCB 75 is ring shaped and
extends round the inner duct 310 between the inner duct 310 and the
outer wall 360. The PCB 75 is in fluid communication with the
primary fluid flow path 400. The PCB 75 extends about the fluid
flow path 300 and is isolated from the fluid flow path 300 by the
inner duct 310.
[0040] The PCB 75 controls parameters such as the temperature of
the heater 80 and the speed of rotation of the fan unit 70.
Internal wiring (not shown) electrically connects the PCB 75 to the
heater 80 and the fan unit 70 and the cable 50. Control buttons 62,
64 are provided and connected to the PCB 75 to enable a user to
select from a range of temperature settings and flow rates for
example.
[0041] Downstream of the PCB 75, is the heater 80 and a PCB baffle
700 is provided between the PCB 75 and the heater 80. The PCB
baffle provides thermal protection for the PCB 75 when the heater
80 switched on amongst other things.
[0042] In use, fluid is drawn into the primary fluid flow path 400
by the action of the fan unit 70, is optionally heated by the
heater 80 and exits from the primary fluid outlet 440. This
processed flow causes fluid to be entrained into the fluid flow
path 300 at the fluid inlet 320. The fluid combines with the
processed flow at the second end 34 of the body. In the example
shown in FIG. 2, the processed flow exits the primary fluid outlet
440 and the hairdryer as an annular flow which surrounds the
entrained flow that exits from the hairdryer via the fluid outlet
340. Thus fluid that is processed by the fan unit and heater is
augmented by the entrained flow.
[0043] The body 30 is generally symmetrical about a longitudinal
axis A-A which extends along the length of the body 30. The duct
310 and outer wall 360 are concentric as is the heater 80 located
between the duct 310 and the outer wall 360.
[0044] Referring now to FIGS. 3 to 6 in particular, the heater 80
comprises a wall 180 which surrounds the heater element 82 and
extends around the external periphery of the heater element 82
providing some thermal protection to the outer wall 360 of the body
30 of the hairdryer 10. The heater element 82 is supported by a
scaffold consisting of an inner tube 84 and a plurality of
supporting struts 86 which extend radially between the inner tube
84 and the wall 180 and around which the heater element 82 is
wound.
[0045] In order to prevent the heater element 82 from overheating,
for example if the primary fluid inlet becomes blocked, a thermal
safety device is provided. In this embodiment, the thermal safety
device is a bi-metallic strip 280. When a pre-determined fluid
temperature is reached the bi-metallic strip 280 bends breaking an
electrical contact and the heater circuit 88. Once the fluid around
the bi-metallic strip 280 cools sufficiently, the electrical
contact is re-established and the heater circuit 88 is complete
allowing the heater 80 to function again.
[0046] The bi-metallic strip 280 is upstream of the heater 80 so it
does not sit within heated fluid. Thus, to enable the bi-metallic
strip 280 to function effectively, a pre-heater 290 is provided.
The pre-heater 290 forms part of the heater circuit 88 and is
located fluidly upstream of the bi-metallic strip 280. The
pre-heater 290 has a resistive element 292 which experiences the
same current and fluid flow as the heater element 82 and is
designed to simulate having the bi-metallic strip 280 within the
heater 80.
[0047] The wall 180 which surrounds the heater element 82 and
extends around the external periphery of the heater element 82
additionally extends over the pre-heater 290 to providing thermal
protection to the outer wall 360 of the body 30 of the hairdryer 10
from heat generated by the pre-heater 290. In this embodiment the
wall extension 182 is localised around the pre-heater 290.
[0048] When the hairdryer is switched on using the on/off button
62, current passes through a heater circuit 88. In this embodiment,
a pair of thermal fuses 250 is provided as a part of the thermal
safety for the hairdryer. The thermal fuses 250 render the
appliance inoperable permanently if the fuse wire within melts. The
thermal fuses 250 are positioned within the live wire 188 of the
heater circuit 88 after the on/off button 62 but before the heater
80 and motor 70 so if there is a problem with the power supply to
the hairdryer causing the thermal fuses 250 to activate, the heater
80 and motor 70 are not switched on. The bi-metallic strip is next
in the heater circuit 88, again so if the bi-metallic strip bends
and breaks the circuit, power to the heater 80 stops until a
pre-determined lower temperature is reached. The pre-heater 290
follows the bi-metallic strip 280 in the heater circuit 88 and then
the heater 80. The live wire 188 continues to the PCB and the motor
70.
[0049] In this embodiment, there are two heater elements 82a, 82b
and a temperature setting button 64. Each heater element 82a, 82b
is connected to the heater button 64 via a neutral wire 164, Triacs
(not shown) on the PCB respond to a user pressing the temperature
setting button 64 and regulate the power through the heater
elements 82a, 82b to provide a range of different temperature
settings for the hairdryer.
[0050] The bi-metallic strip 280 is positioned orthogonal to the
fluid flow in the body 30, thus it is orthogonal to the
longitudinal axis of the body A-A. This is advantageous as it
maximises the exposure of the bi-metallic strip 280 to the fluid
flowing through the primary fluid flow path 400. The pre-heater 290
is also positioned so the resistive element 292 is orthogonal to
the fluid flow, ideally the resistive element 292 extends across
the whole of the bi-metallic strip 280 as this maximises the
effectiveness of this safety feature.
[0051] The pre-heater 290 has a resistive element 292 that extends
partially around the primary fluid flow path 400 and is a single
row of wire bent unto undulations. As an alternative, the wire
could be formed into a coil. The resistive element 292 could form a
ring that extends all the way round the flow path. The essential
feature is not determined by the shape of the resistive element
292; it is that the bi-metallic strip 280 experiences either an
equivalent temperature to if it were actually located within the
heater 80 or that the pre-heater and the bi-metallic strip are
attuned and both related to the heater temperature. Thus, the
pre-heater 290 and the bi-metallic strip 280 may function at a
different temperature to that of the heater 80.
[0052] The invention has been described in detail with respect to a
hairdryer however, it is applicable to any appliance that draws in
a fluid and directs the outflow of that fluid from the
appliance.
[0053] The fluid that flows through the appliance is generally air,
but may be a different combination of gases or gas and can include
additives to improve performance of the appliance or the impact the
appliance has on an object the output is directed at for example,
hair and the styling of that hair.
[0054] The invention is not limited to the detailed description
given above. Variations will be apparent to the person skilled in
the art. In particular, the heater may be a conventional heater
which is trapezoid in shape and wound around a frame formed into a
cross shape. The heater may comprise more or less heater elements
than has been herein described.
* * * * *