CLEANER HEAD FOR A VACUUM CLEANER
A cleaner head for a vacuum cleaner that comprises a pair of rotary agitators and one or more wheels. The agitators rotate in opposite directions, and the wheels are moveable between a deployed position and a retracted position. The wheels contact a floor to be cleaned when in the deployed position, and the wheels are lifted clear of the floor when in the retracted position such that the cleaner head is supported on the floor solely by the agitators.
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This application claims priority to United Kingdom Application No. 1700330.2, filed Jan. 9, 2017, the entire contents of which are incorporated herein by reference.
FIELD OF THE INVENTIONThe present invention relates to a cleaner head for a vacuum cleaner.
BACKGROUND OF THE INVENTIONThe cleaner head of a vacuum cleaner may comprise a rotary agitator mounted within a housing. Wheels are often provided on the base of the housing to ensure that, as the cleaner head is manoeuvred over a floor, the housing does not contact and potentially damage the floor. Unfortunately, the wheels tend to constrain movement of the cleaner head to forward and rearward motion only.
SUMMARY OF THE INVENTIONAccording to some embodiments, a cleaner head comprises a pair of rotary agitators and one or more wheels, wherein the agitators rotate in opposite directions, the wheels are moveable between a deployed position and a retracted position, the wheels contact a floor to be cleaned when in the deployed position, and the wheels are lifted clear of the floor when in the retracted position such that the cleaner head is supported on the floor solely by the agitators.
When the wheels are in the retracted position, the cleaner head is supported on the floor solely by the agitators. Consequently, when the agitators are rotating, there is no (or relatively little) static friction between the cleaner head and the floor. The cleaner head therefore appears to hover and requires relatively little force in order to manoeuvre the cleaner head over the floor. The rotation of each agitator generates traction. However, since the agitators rotate in opposite directions, the forward traction generated by the front agitator is opposed by the rearward traction generated by the rear agitator. When the wheels are in the deployed position, the cleaner head is additionally supported by the wheels. Again, there is no (or relatively little) static friction between the agitators and the floor. The wheels, however, act to constrain movement of the cleaner head along a linear path.
The cleaner head may therefore be said to operate in one of two modes depending on the position of the wheels: hover mode and linear mode. Hover mode has the advantage that the cleaner head may be moved freely in all directions. In particular, the cleaner head may be moved from side to side in addition to forwards and rearwards, thus making it easier to manoeuvre the cleaner head between narrow gaps or to sweep the cleaner head sideways beneath furniture. A disadvantage with hover mode is that it can be difficult to steer the cleaner head in a particular direction. Linear mode has the advantage of providing better control over the direction of travel of the cleaner head.
The agitators and the wheels may rotate about fixed axes of rotation that are parallel to one another. Consequently, when the wheels are deployed, the cleaner head is constrained to move in a direction normal to the rotational axes of the agitators. This then has the advantage that, when the cleaner head comprises two elongate agitators located towards the front and rear of the cleaner head, the cleaner head is constrained by the wheels to move in forward and rearward directions.
The wheels may comprise a pair of wheels located on opposite sides of the cleaner head at positions between the agitators. As a result, when the wheels are in the deployed position, the housing and the agitators may tip forwards or rearwards in response to a push or pull force applied to the cleaner head. Tipping of the housing will increase the traction generated by one of the agitators and decrease the traction generated by the other of the agitators. As a result, a smaller push or pull force is required to manoeuvre the cleaner head. The wheels may be located midway between the two agitators such that the same degree of forward and rearward tipping may be achieved in response to push and pull forces of the same magnitude.
The cleaner head may comprise a housing within which the agitators are rotatably mounted, and a neck pivotally attached to the top of housing at a position between the agitators. A push or pull force may then be applied to the neck in order to manoeuvre the cleaner head forwards or rearwards. The push or pull force is then transferred from the neck to the housing at the pivot attachment. If the neck were pivotally attached at a position towards the rear of the housing, as is often the case with conventional cleaner heads, the housing and agitators would most likely tip rearwards in response to a push force. As a result, the forward traction generated by the front agitator will decrease and the rearward traction generated by the rear agitator will increase. There is therefore a net increase in rearward traction when attempting to push the cleaner head forwards. Likewise, the housing and agitators would most likely tip forwards in response to pull force such that there is a net increase in forward traction when attempting to pull the cleaner head rearwards. Since the net change in traction acts in a direction opposite to the applied force, larger push and pull forces are required in order to manoeuvre the cleaner head. By pivotally attaching the neck to the housing at a position between the two agitators, tipping of the housing and agitators in response to push and pull forces may be reduced. As a result, smaller push and pull forces are required to manoeuvre the cleaner head forwards and rearwards. The neck may be pivotally attached to the top of the housing at a position midway between the agitators. As a result, the vertical component of the push or pull force is distributed evenly between the two agitators and thus there is no net torque exerted on the housing by the vertical component of the force.
The agitators may be identical and may rotate at the same speed. By employing identical agitators that rotate at the same speed, the forward traction generated by the front agitator may be equal and opposite to the rearward traction generated by the rear agitator. This then has the advantage that, in the absence of a push or pull force, there is no net movement of the cleaner head.
In order that the present invention may be more readily understood, an embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:
The cleaner head 1 of
The housing 2 defines a chamber 8 within which the agitators 3,4 are rotatably mounted. Each agitator 3,4 comprises an elongate body 11 to which bristles, flicker strips or other means 12 for agitating a surface are attached. In the present embodiment, the elongate body 11 is covered with a plush of synthetic fibres 12. The two agitators 3,4 rotate in opposite directions about axes of rotation 13,14 that are parallel to one another. More particularly, the agitators 3,4 rotate in directions that act to sweep dirt from the floor into the chamber 8. Consequently the front agitator 3 in
The drive assembly 5 is mounted within the housing 2 and comprises an electric motor 15 and a gear train 16 for transmitting torque generated by the motor 15 to each of the agitators 3,4. The particular details of the drive assembly 5 are not pertinent to the present invention. Accordingly, rather than a single motor 15 that is used to drive both agitators 3,4, the drive assembly 5 may comprise two electric motors, each driving a respective agitator 3,4. Alternatively, rather than an electric motor 15, the drive assembly 5 may comprise an air turbine to generate the torque necessary to drive the agitators 3,4. Equally, the torque generated by the electric motor 15 may be transmitted to the agitators 3,4 by alternative means, such as a belt and pulley.
The wheel assembly 6 comprises a pair of wheels 20,21 mounted on opposite sides of the housing 2. The wheels 20,21 rotate about axes of rotation that are parallel to the axes of rotation of the agitators 3,4. Each wheel 20,21 is moveable vertically between a deployed position and a retracted position. The wheel assembly 6 further comprises a pair of actuators (not shown) mounted within the housing 2. Each actuator is coupled to a respective wheel 20,21 and, when actuated, moves the wheel 20,21 between the deployed and retracted positions. When the cleaner head 1 is resting on a floor, the wheels 20,21 contact the floor when in the deployed position and are lifted clear of the floor when in the retracted position. As explained below, the behaviour of the cleaner head 1 differs according to the position of the wheels 20,21.
The neck 7 is pivotally attached to the top of the housing 2. The neck 7 pivots relative to the housing 2 about a pivot axis 25 that is parallel to the rotational axes 13,14 of the agitators 3,4. The neck 7 is pivotally attached to the housing 2 at positions midway between the two agitators 3,4. As a result, the pivot axis 25 of the neck 7 is equidistant from the rotational axes 13,14 of the agitators 3,4, the significance of which is discussed below. The neck 7 comprises a conduit 26 that extends from an outlet 27 located at a free end of the neck 7 to a suction port 9 formed in the top of the housing 2. The neck 7 further comprises electrical terminals 28, and electrical cables 29 that extend from the terminals 28 to the electric motor 20 and to the actuators. The free end of the neck 7 is attachable to a tube of a vacuum cleaner (not shown). The tube is then used to manoeuvre the cleaner head 1 as well as deliver electrical power to the motor 20 and actuators via the electrical terminals 28.
During use, suction generated at the outlet 27 of the cleaner head 1 causes air to be drawn beneath the two agitators 3,4 and into the chamber 8. From there, the air is drawn through the suction port 9 and along the conduit 26 of the neck 7. The agitators 3,4, as they rotate, sweep dirt into the chamber 8. The dirt swept into the chamber 8 then becomes entrained in the air moving through the cleaner head 1.
When the wheels 20,21 are in the retracted position, the cleaner head 1 is supported on the floor solely by the agitators 3,4. That is to say that no other part of the cleaner head 1 contacts the floor. Since only the agitators 3,4 contact the floor and each agitator 3,4 comprises a body 11 covered with a plush of fibres 12, the likelihood of the cleaner head 1 scratching or otherwise marking the floor is reduced. When the agitators 3,4 rotate, there is no (or relatively little) static friction between the cleaner head 1 and the floor. As a result, the cleaner head 1 appears to hover and requires relatively little force in order to move the cleaner head 1. Moreover, the cleaner head 1 can be moved freely in all directions. The rotation of each agitator 3,4 generates traction. However, since the two agitators 3,4 rotate in opposite directions, the forward traction generated by the front agitator 3 is opposed by the rearward traction generated by the rear agitator 4. Moreover, since the two agitators 3,4 are structurally identical (i.e. same elongate body 11 and agitation means 12) and rotate at the same speed, the forward traction generated by the front agitator 3 is equal and opposite to the rearward traction generated by the rear agitator 4. As a result, there is no net movement of the cleaner head 1.
When the wheels 20,21 are in the deployed position, the cleaner head 1 is supported on the floor by both the agitators 3,4 and the wheels 20,21. Owing to the contact between the wheels 20,21 and the floor, the agitators 3,4 are raised slightly relative to the floor. Again, due to the rotation of the agitators 3,4, there is no (or relatively little) static friction between the agitators 3,4 and the floor. Consequently, the cleaner head 1 may be manoeuvred over the floor with relatively little force. The wheels 20,21 act to constrain movement of the cleaner head 1 in a generally forward-rearward direction. As the cleaner head 1 moves forward and rearwards, steering to the left and right may be achieved by rotating or twisting the neck 7 about its longitudinal axis. However, purely sideways movement of the cleaner head 1 is prevented by the wheels 20,21.
The cleaner head 1 may be said to operate in one of two modes depending on the position of the wheels: hover mode and linear mode. Hover mode has the advantage that the cleaner head 1 may be moved freely in all directions. In particular, the cleaner head 1 may be moved from side to side in addition to forwards and rearwards, thus making it easier to manoeuvre the cleaner head 1 between narrow gaps or to sweep the cleaner head 1 sideways beneath furniture. A disadvantage with hover mode is that it can be difficult to steer the cleaner head 1 in a particular direction. Linear mode has the advantage of providing better control over the direction of travel of the cleaner head 1. The wheels 20,21 act to constrain movement of the cleaner head 1 in a forward-rearward direction and thus a user is better able to steer the cleaner head 1. The user may switch between the two modes during use by actuating the actuators. This may be achieved, for example, by depressing a button provided on a handle of the vacuum cleaner.
When manoeuvring the cleaner head 1 forwards, a push force is exerted on the neck 7 of the cleaner head 1. The push force is transferred from the neck 7 to the housing 2 at the pivot attachment. The push force exerted on the housing 2 may be resolved into a vertical component and a horizontal component. The vertical component acts in a downward direction. Since the neck 7 is pivotally attached to the housing 2 at positions midway between the two agitators 3,4, the vertical component is distributed evenly between the two agitators 3,4. As a result, no net torque is generated by the vertical component, which would otherwise cause the housing 2 and agitators 3,4 to tip forwards or rearwards. The horizontal component causes the cleaner head 1 to move forwards. Additionally, the horizontal component causes the housing 2 and the agitators 3,4 to tip forwards slightly. Tipping arises because the horizontal component of the push force acts at a position that is higher than the kinetic friction of the floor. The degree of tipping is relatively small since any tipping can only be brought about through compression of the front agitator 3. However, as a result of the tipping, albeit small, the forward traction generated by the front agitator 3 is no longer equal to the rearward traction generated by the rear agitator 4, but is instead slightly greater. As a result, a smaller push force is required to manoeuvre the cleaner head 1 forwards. Indeed, depending on the characteristics of the cleaner head 1 (e.g. the weight of the cleaner head 1, the traction generated by each agitator 3,4) and the surface type of the floor, the net forward traction may be greater than the kinetic friction. In this instance, the cleaner head 1 would propel itself forwards in response to the initial push force.
A similar behaviour occurs when a pull force is exerted on the neck 7 in order to manoeuvre the cleaner head 1 rearwards. Again, the pull force is transferred from the neck 7 to the housing 2 at the pivot attachment and may be resolved into a vertical component and a horizontal component. The vertical component now acts in an upward direction. But again, since the neck 7 is pivotally attached to the housing 2 at positions midway between the two agitators 3,4, the vertical component is transferred equally between the two agitators 3,4. The horizontal component causes the cleaner head 1 to move rearwards. Owing to the kinetic friction from the floor, the horizontal component causes the housing 2 and the agitators 3,4 to tip rearwards slightly. As a result of the tipping, the rearward traction generated by the rear agitator 4 is slightly greater than the forward traction generated by the front agitator 3. A smaller pull force is therefore required to manoeuvre the cleaner head 1 rearwards. Moreover, if the net rearward traction is greater than the kinetic friction, the cleaner head 1 will propel itself rearwards in response to the initial pull force.
The behaviour described above occurs irrespective of the position of the wheels 20,21. However, the behaviour is magnified when the wheels 20,21 are in the deployed position. The reason for this is that, when the wheels 20,21 are in the deployed position, the agitators 3,4 are raised further from the floor. Consequently, the housing 2 and the agitators 3,4 are able to tip through a larger angle in response to the same push or pull force. By tipping through a larger angle, the difference between the forward traction of the front agitator 3 and the rearward traction of the rear agitator 4 is greater. As a result, a smaller push/pull force is generally required to manoeuvre the cleaner head 1 forwards/rearwards when the wheels 20,21 are in the deployed position.
In the embodiment described above, the wheels 20,21 are located on opposite sides of the housing 2. Moreover, the wheels 20,21 are located at positions midway between the two agitators 3,4. This then has the advantage that, when the wheels 20,21 are in the deployed position, the housing 2 and the agitators 3,4 continue to tip forwards and rearwards in response to push and pull forces. In spite of this advantage, the cleaner head 1 could conceivably have an alternative arrangement of wheels. For example, the cleaner head 1 may comprise a pair of wheels located on each side of the housing 2, with each pair comprising a first wheel located forward of the front agitator 3 and a second wheel located rearward of the rear agitator 4. Consequently, when the wheels 20,21 are in the deployed position, tipping of the housing 2 and agitators 3,4 in response to a push or pull force is prevented. As a further example, the cleaner head 1 may comprise a single wheel, such as an elongate roller, that is located, for example, at the rear of the housing 2 or at the centre of the housing 2 between the two agitators 3,4. Irrespective of the number and location of the wheels, the wheels continue to be moveable between a deployed position in which the wheels contact the floor, and a retracted position in which the wheels are lifted clear of the floor. As a result, the cleaner head 1 continues to have a hover mode and a linear mode.
In the embodiment described above, the wheels 20,21 are moved vertically by electrical actuators when moving between the deployed and retracted positions. The wheels 20,21 may, however, be moved in alternative ways using alternative means. For example, rather than moving vertically up and down, the wheels 20,21 may instead pivot or swing up and down in a movement akin to the front landing gear of an aeroplane. Moreover, movement of the wheels 20,21 may be achieved using mechanical rather than electrical actuation.
The two agitators 3,4 are structurally identical and rotate at the same speed. This then has the advantage that, when the agitators 3,4 rotate, the forward traction generated by the front agitator 3 is equal and opposite to the rearward traction generated by the rear agitator 4. Nevertheless, the cleaner head 1 could conceivably comprise agitators that are structurally different and/or agitators that rotate at different speeds. Indeed, it is quite possible that different agitators rotating at different speeds may continue to generate traction forces that are equal and opposite.
Claims
1. A cleaner head for a vacuum cleaner, the cleaner head comprising a pair of rotary agitators and one or more wheels, wherein the agitators rotate in opposite directions, the wheels are moveable between a deployed position and a retracted position, the wheels contact a floor to be cleaned when in the deployed position, and the wheels are lifted clear of the floor when in the retracted position such that the cleaner head is supported on the floor solely by the agitators.
2. The cleaner head of claim 1, wherein the agitators and the wheels rotate about axes of rotation that are parallel to one another.
3. The cleaner head of claim 1, wherein the wheels comprise a pair of wheels located on opposite sides of the cleaner head at positions between the agitators.
4. The cleaner head of claim 1, wherein the wheels are located midway between the agitators.
5. The cleaner head of claim 1, wherein the cleaner head comprises a housing within which the agitators are rotatably mounted, and a neck pivotally attached to the top of housing at a position between the agitators.
6. The cleaner head of claim 5, wherein the neck is pivotally attached to the top of the housing at a position midway between the agitators.
7. The cleaner head of claim 1, wherein the agitators are identical and rotate at the same speed.
Type: Application
Filed: Jan 5, 2018
Publication Date: Jul 12, 2018
Applicant: Dyson Technology Limited (Wiltshire)
Inventor: Oliver DODGSON (Swindon)
Application Number: 15/863,617
