Autonomous cleaner

An autonomous cleaner includes: a cleaner body; a cleaning module protruded from one side of the cleaner body, and having a castor; caterpillar units provided at both sides of the cleaner body, and positioned at a rear side of the cleaning module, wherein the caterpillar unit includes: a driving module; a driving wheel mounted to the driving module, and formed to be rotatable by receiving a driving force from the driving module; a driven wheel mounted to the driving module, and provided at a rear side of the driving wheel; and a belt formed to entirely enclose the driving wheel and the driven wheel as a closed loop, and configured to rotate the driven wheel when the driving wheel is rotated. The cleaner body is supported on a floor surface by the castor and the driven wheel, or by the driving wheel and the driven wheel.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Korean Application No. 10-2017-0086098, filed on Jul. 6, 2017, whose entire disclosure is hereby incorporated by reference.

BACKGROUND

This specification relates to an autonomous cleaner having caterpillar units (or continuous track units) for moving a cleaner body.

A cleaner is an apparatus for performing a cleaning function by sucking dust or foreign materials or through a mopping operation. Generally, the cleaner performs a cleaning function with respect to a floor, and includes wheels for movement. Generally, the wheels are moved by an external force applied to the cleaner body, and are configured to move the cleaner body on a floor.

However, recently, research on an autonomous cleaner such as a robot cleaner which performs a cleaning function while autonomously moving without a user's manipulation, and a cleaner which moves autonomously along a nozzle moved according to a user's manipulation, is actively ongoing.

Such an autonomous cleaner is generally provided with a driving wheel rotated by receiving a driving force from a driving motor. However, a belt driving type caterpillar (also known as a continuous track) rather than the driving wheel has been introduced recently. The reason is because an ascending performance of the autonomous cleaner can be more enhanced by the caterpillar than the driving wheel, and a moving performance can be obtained even on a soft floor such as a carpet. However, it is difficult to maintain a moving performance of the autonomous cleaner at a floor environment which changes every moment. Thus, one of researchers' tasks is to develop a design for stably obtaining a moving performance.

In order to stably obtain a moving performance, a cleaner body should be stably supported on a floor surface, firstly (first condition). Secondly, the caterpillar or the driving wheel should maintain a contacted state to a floor, even if a state of a condition of the floor is changed (second condition). Thirdly, an impact generated while the autonomous cleaner is moving should be attenuated (third condition).

FIGS. 1A, 1B, 2A and 2Bare views showing a robot cleaner (or an autonomous cleaner) to which a caterpillar device shown in patent documents has been applied. With regards to the first condition, Korean Laid-Open Patent Publication No. 10-2016-0138812 (hereinafter, will be referred to as patent document 1) discloses an auxiliary wheel15″ and a caterpillar type main wheel15′ (as shown inFIGS. 1A and 1B). And European Laid-Open Patent Publication No. 2891440 (hereinafter, will be referred to as patent document 2) discloses a plurality of rollers31and a caterpillar type traction unit20(as shown inFIGS. 2A and 2B).

However, in the above structure, caterpillars are provided on right and lefts sides of a cleaner body, and a belt of the caterpillars comes in linear-contact with a floor surface. Therefore, the cleaner body should be provided with a castor or wheel in order to maintain its horizontal state. If the castor is provided at the cleaner body, a moving resistance due to the castor is increased. This may lower a moving performance.

With regards to the second condition, the patent document 1 discloses a configuration that driven wheels15b,15chaving a smaller diameter than a driving wheel15aare provided at both sides of the driving wheel15a, in an upward-spaced state from a floor surface (seeFIGS. 1A and 1B). And the patent document 2 discloses a configuration that a driving wheel94having a smaller diameter than a driven wheel96is provided at a front upper side of the driven wheel96in a spaced manner (seeFIGS. 2A and 2B).

In the above structure, when an inclination angle of the caterpillars with respect to the floor surface is large, an ascending performance (a climbing performance) of the robot cleaner (or the autonomous cleaner) is enhanced. However, in this case, a moving performance of the robot cleaner (or the autonomous cleaner) is lowered, because a contact area of the belt of the caterpillars with the floor surface is reduced when the robot cleaner moves on a soft floor (e.g., a carpet, a rug, etc.). Thus, it is difficult to maintain a moving performance of the autonomous cleaner at a floor environment which changes every moment.

With regards to the third condition, the patent document 2 discloses a swing arm92which elastically moves a driven wheel96clockwise or counterclockwise on the basis of a driving wheel94. In the above structure, the driving wheel94is fixed to the cleaner body. Accordingly, if an impact is directly applied to the driving wheel94, the impact may be transferred to the cleaner body.

DETAILED DESCRIPTION

Hereinafter, an autonomous cleaner according to the present disclosure will be explained in more detail with reference to the attached drawings.

FIG. 3is a perspective view showing an autonomous cleaner100according to a first embodiment of the present disclosure, andFIG. 4is a side sectional view of the autonomous cleaner100shown inFIG. 3.FIGS. 3 and 4show a first embodiment of the autonomous cleaner100which performs a function to clean a floor while autonomously moving on a predetermined region. The function to clean a floor includes a function to suck dust on a floor, or a function to mop a floor.

The autonomous cleaner100includes a cleaner body110, a cleaning module (or cleaning head)120and caterpillar units (or caterpillar tracks)130. The cleaner body110forms an appearance of the autonomous cleaner100. Various types of components including a controller (not shown) for controlling the autonomous cleaner100are mounted to the cleaner body110.

A dust container160is detachably mounted to the cleaner body110, and a dust container cover170for covering the dust container160is provided. In an embodiment, the dust container cover170may be hinge-coupled to the cleaner body110so as to be rotatable.

The dust container cover170may be fixed to the dust container160or the cleaner body110to cover an upper surface of the dust container160. In the state that the dust container cover170is arranged to cover the upper surface of the dust container160, the dust container160may be prevented from being separated from the cleaner body110due to the dust container cover170.

The dust container cover170may be provided with a handle171, and a button portion173may be provided at the handle171. A user may rotate the dust container cover170by pressing the button portion173with holding the handle171. As a result, the dust container160is in a separable state from the cleaner body110.

A sensing unit (or sensor)172for sensing a peripheral situation may be provided at the cleaner body110. The sensing unit172may include a sensor (not shown) for sensing an obstacle or a terrain feature, and the controller for generating a map of a driving region based on sensed data. In the drawings, the sensor of the sensing unit172is provided at a front side of the handle171so as to sense a front side and an upper side.

The cleaning module120is configured to suck dust-included air or to clean a floor. The cleaning module120for sucking dust-included air may be referred to as a suction module, and the cleaning module120for cleaning a floor may be referred to as a mop module.

The cleaning module120may be detachably coupled to the cleaner body110. Once the suction module is separated from the cleaner body110, a mop module may be detachably coupled to the cleaner body110by replacing the separated suction module. Accordingly, a user may mount a suction module to the cleaner body110in case of removing dust on a floor, and may mount a mop module to the cleaner body110in case of mopping a floor. The cleaning module120may be also configured to suck dust-included air, and then to mop a floor.

The cleaning module120is protruded from one side of the cleaner body110. The one side may be a forward driving side of the cleaner body110, i.e., a front side of the cleaner body110.

In the drawings, the cleaning module120is protruded from one side of the cleaner body110, towards a front side and right and left sides. More specifically, a front end of the cleaning module120is arranged at a position forward spaced apart from one side of the cleaner body110. And right and left ends of the cleaning module120are arranged at positions spaced apart from one side of the cleaner body110right and left.

A castor (or wheel)121is provided at the cleaning module120. The castor121is configured to assist a driving of the autonomous cleaner100, and to support the autonomous cleaner100together with caterpillar units130to be explained later. A structure to support the autonomous cleaner100by the caterpillar units130and the castor121will be explained later in more detail.

The cleaner body110is provided with the caterpillar units130. The caterpillar units130are formed to be rotatable by receiving a driving force from driving motors134a(seeFIG. 8). A driving direction of the driving motor134amay be controlled by the controller, and the caterpillar units130may be rotatable in one direction or another direction.

The caterpillar units130may be provided on right and left sides of the cleaner body110. The caterpillar units130may be formed to be driven independently from each other. For instance, the caterpillar units130may be formed to be rotated in different directions at different speeds by the driving motors134a. With such a configuration, the cleaner body110may be moved or rotated right and left and back and forth.

Further, the caterpillar unit130linearly-contact a floor in order to support the cleaner body110, and is provided with a suspension135(refer toFIG. 7) in order to enhance a grip force. This will be explained later in more detail.

A moving performance of the autonomous cleaner100is determined by the castor121, the caterpillar units130and the suspensions135. However, as aforementioned in the above background of the disclosure, the structure disclosed in the patent documents has the following problems.

Firstly, once the castor is installed at the cleaner body, a moving resistance occurs by the castor. This may cause a moving performance of the autonomous cleaner100to be lowered. Secondly, if the caterpillar units linearly-contact a floor regardless of a state of the floor, the moving performance of the autonomous cleaner100is lowered in a situation where a high grip force is required. Thirdly, in a suspension structure having a swing arm92as shown in the patent document 2, a buffering effect cannot be uniformly obtained according to a driving direction due to the suspension design structure. This may cause the moving performance to be lowered in a specific situation. Hereinafter, a structure which has overcome the problems will be explained in more detail.

FIG. 5is a conceptual view showing a state that the autonomous cleaner100shown inFIG. 3is positioned on a hard floor, andFIG. 6is a conceptual view showing a state that the autonomous cleaner100shown inFIG. 3is positioned on a soft carpet.FIGS. 7 and 8are views of the caterpillar unit130. For reference,FIGS. 7 and 8show a shaded belt133.

In the drawings, the caterpillar unit130includes a driving wheel131which supports and moves the autonomous cleaner100, a driven wheel132, the belt133, driving devices (i.e., a driving module134and a housing136), and the suspension135for protecting the cleaner body110from an external shock.

Firstly, the driving wheel131, the driven wheel132and the belt133of the caterpillar unit130will be explained. The driving wheel131is rotatably mounted to the cleaner body110, and is rotated by receiving a driving force from the driving module134to be explained later. More specifically, the driving wheels131are mounted to both sides of the cleaner body110, and is configured to rotate the belt133clockwise or counterclockwise by rotation.

The driven wheel132is mounted to the cleaner body110in the same way as the driving wheel131, and is arranged at a rear side of the driving wheel131. The driven wheel132is engaged with the belt133, and is rotated together with the belt133by a rotational force of the belt133. The driven wheel132is configured to support the autonomous cleaner100together with the castor121provided at the cleaning module120.

Concavo-convex portions131a,132amay be formed on outer circumferential surfaces of the driving wheel131and the driven wheel132, in order to increase a frictional force with the belt133. In the drawings, the concavo-convex portions131a,132aare formed on the outer circumferential surfaces of the driving wheel131and the driven wheel132, in order to be engaged with a concavo-convex portion133bformed on an inner circumferential surface of the belt133(refer toFIG. 9).

The caterpillar unit130may come in planar or linear-contact with a floor according to an arranged state of the driving wheel131and the driven wheel132. With such a configuration, a structure to support the cleaner body110, or a grip force of the caterpillar unit130may be changed.

In the drawings, the autonomous cleaner100is supported by the castor121and the driven wheel132. More specifically, the driving wheel131is arranged at a front side of the driven wheel132, and is spaced apart from a floor. Accordingly, the caterpillar unit130is configured to linearly contact a floor by the driven wheel132.

The driving wheel131may be upward arranged to have a tilt angle (θ) with respect to the driven wheel132. Here, the tilt angle (θ) may be more than 1° and less than 5°. If the tilt angle (θ) is within the range, the caterpillar unit130come in linear-contact with a hard floor, and come in planar-contact with a soft floor. This may allow a stable moving performance of the autonomous cleaner100to be obtained.

On the other hand, if the tilt angle (θ) is less than 1°, the caterpillar unit130may unintentionally come in planar-contact with a floor according to a state of the floor. For instance, if a floor has a rough surface, the caterpillar unit130may unintentionally come in planar-contact with the floor while moving. As another example, if the tilt angle (θ) exceeds 5°, the belt133of the caterpillar unit130may not come in planar-contact with a floor on a soft carpet.

Referring toFIGS. 5 to 7, the driving wheel131is arranged at a front side of the driven wheel132, and is spaced apart from a floor by a distance corresponding to the tilt angle (θ). With such a configuration, since the caterpillar unit130comes in linear-contact with a hard floor (e.g., a bare floor or a papered floor), a high driving speed of the autonomous cleaner100may be obtained. On the other hand, in case of a soft floor requiring a high grip force (e.g., a carpet, a rug, etc.), the belt133comes in planar-contact with the floor. This may allow a stable moving performance of the autonomous cleaner100to be obtained.

In the drawings, a diameter of the driving wheel131provided at a front side of the cleaner body110is formed to be larger than that of the driven wheel132. Generally, when a diameter of a wheel is large, an ascending performance of the autonomous cleaner100is enhanced because an ascending resistance to a moving direction is reduced. Accordingly, if the driving wheel131is larger than the driven wheel132, the autonomous cleaner100has a higher ascending performance when moving forward than when moving backward.

However, the present disclosure is not limited to this. That is, the driving wheel331and the driven wheel332may have the same diameter such that the autonomous cleaner100may have the same ascending performance when moving forward and backward.

The belt133is formed to entirely enclose (or encircle) the driving wheel131and the driven wheel132, thereby forming a closed loop. Once the driving wheel131is rotated by receiving a driving force from the driving module134, the belt133interlocked with the driving wheel131is rotated together in a rotation direction of the driving wheel131. In this case, the driven wheel132engaged with the belt133is also rotated as the belt133is rotated.

The belt133is integrally rotated with the driving wheel131and the driven wheel132to generate a frictional force with a floor, thereby allowing the autonomous cleaner100to move on a floor. The belt133is formed of an elastically transformable material (e.g., rubber, urethane, etc.). A concavo-convex portion133amay be formed on an inner circumferential surface of the belt133, in order to increase a frictional force with the driving wheel131and the driven wheel132. Further, a concavo-convex portion133bmay be formed on an outer circumferential surface of the belt133, in order to increase a frictional force with a floor. In an embodiment, the belt133may be formed as a timing belt.

An empty space where the belt133is elastically transformable towards the inside of the caterpillar unit130may be formed between the driving wheel131and the driven wheel132. This is in order to provide an available space where the belt133is transformable by an obstacle while the autonomous cleaner100is ascending (climbing) the obstacle.

A wheel cover137may be provided to cover one side surface of the driving wheel131and the driven wheel132, in order to protect the driving wheel131and the driven wheel132from an external environment. In the drawings, the wheel cover137covers not only an outer side surface of the driving wheel131and the driven wheel132, but also an outer side surface of a space defined by the driving wheel131, the driven wheel132and the belt133. However, the present disclosure is not limited to this. That is, the wheel cover137may be configured to cover a part of one side surface of the driving wheel131and the driven wheel132. With such a configuration, foreign materials may be prevented from being introduced into the caterpillar unit130, and the driving wheel131and the driven wheel132may be protected from physical damage such as a scratch occurring while the autonomous cleaner100is moving.

Next, the driving module134and the housing136of the caterpillar unit130will be explained.FIG. 9is an exploded perspective view of the caterpillar unit130shown inFIG. 7.FIG. 10is a view of the caterpillar unit130shown inFIG. 9, which shows components except for wheel-related components. AndFIG. 11is a rear view of the caterpillar unit130shown inFIG. 7.

In order to drive the autonomous cleaner100, the driving module134is provided at the cleaner body110, and is configured to generate a driving force and to transfer the driving force to the driving wheel131. The driving module134includes a driving motor134a, a gear unit (or gears or gear assembly)134band a gear box (or frame)134c.

The driving motor134aincludes a driving part (not shown) for generating a driving force, and an encoder (not shown) for outputting information such as a rotation angle, a speed, etc. of the driving part (not shown) in the form of an electrical signal. The driving motor134ais formed to be rotatable clockwise or counterclockwise, and the controller controls a driving (a rotation direction, a rotation angle, a rotation speed, etc.) of the driving motor134abased on information obtained from the encoder.

The gear unit134bis configured to transfer a driving force generated from the driving motor134ato the driving wheel131. More specifically, the gear unit134bis formed of a plurality of gears. And the gear unit134bis configured to change a rotation speed and a torque of the driving motor134athrough a control of a gear ratio, and to transfer the rotation speed and the torque to the driving wheel131.

The gear box134cforms an appearance of the driving module134, and provides a space where components of the driving module134are fixedly arranged. The housing136to be explained later is connected to one side of the gear box134c, and the driving wheel131and the driven wheel132are rotatably connected to another side of the gear box134c. The connection will be explained later in more detail.

A foreign material introduction preventing unit (or gear cover extension)134c3cfor preventing introduction of foreign materials by covering at least part of a space defined by the driving wheel131, the driven wheel132and the belt133may be protruded from the gear box134c.

In the drawings, the foreign material introduction preventing unit134c3cis arranged to cover a lower space defined by a lower part of the belt133which contacts the driving wheel131, the driven wheel132and a bottom surface. However, the present disclosure is not limited to this. That is, the foreign material introduction preventing unit134c3cmay be arranged to cover an upper space defined by an upper part of the belt133.

The housing136forms an accommodation space for accommodating therein the driving module134and the suspension135to be explained later, and is mounted to the cleaner body110. Referring to the drawings, the housing136is formed to enclose one side of the driving module134. And the housing136may be provided with through holes136aat its upper and lower parts on both sides so as to insert guide bars135aof the suspension135thereinto. A coupling relation between the gear box134cand the gear unit134bwill be explained later.

Next, the suspension135of the caterpillar unit130will be explained. The suspension135is provided between the driving module134and the housing136such that an impact generated from the outside is not transferred to the cleaner body110. More specifically, the suspension135guides the driving module134such that the driving module134moves up and down according to a state of a bottom surface, and attenuates an impact using an elastic member135bto be explained later.

The suspension135includes guide bars135aand elastic members135b. The guide bars135aprovided at the housing136up and down are configured to guide an up-down movement of the driving module134. More specifically, the guide bars135aare inserted into guide holes134c1aformed at both sides of the gear box134c, and are mounted to through holes136aformed at upper and lower parts of the housing136on both sides. With such a configuration, the driving module134is moveable up and down along the guide bars135a. Further, at least one of the guide bars135aand the housing136may be provided with a separation preventing structure for preventing the guide bars135aprovided at the housing136from being separated from the housing136.

The elastic member135bis provided between the driving module134and the cleaner body110. And the elastic member135bis configured to elastically support the driving module134which moves up and down, according to a state of a bottom surface, and to attenuate an impact applied to the autonomous cleaner100. In the drawings, the elastic members135bare formed to enclose the guide bars135a, and are provided between the housing136and the driving module134.

The elastic support means apply an elastic force to the driving module134by the elastic members135b, in an opposite direction to a moving direction of the driving module134, in a compressed or extended state of the elastic members135bby the same distance as a moving distance of the driving module134.

In the drawings, the elastic members135bformed as coil springs are provided between the housing136and the driving module134, with enclosing the guide bars135a. However, the present disclosure is not limited to this. For instance, the elastic members135bmay be formed as plate springs. Under the above structure, a function of the suspension135may be uniformly performed regardless of a driving direction of the autonomous cleaner100. Thus, a driving stability of the autonomous cleaner100may be enhanced.

Next, a structure of the gear unit134band the gear box134cwhich constitute the driving module134will be explained in more detail. The gear unit134bis formed of a plurality of gears, and transfers a driving force generated from the driving motor134ato the driving wheel131. The gear unit134bincludes a first gear portion (or first gear assembly)134b1and a second gear portion (or second gear assembly)134b2.

The first gear portion134b1is rotated in an engaged state with a driving shaft134a1of the driving motor134a. More specifically, a gear formed on an outer circumferential surface of the driving shaft134a1(e.g., a helical gear) is engaged with a gear of the first gear portion134b1, thereby transferring a driving force of the driving motor134ato the first gear portion134b1.

The second gear portion134b2is rotated in an engaged state with the first gear portion134b1and the driving wheel131. More specifically, the second gear portion134b2includes a first sub gear134b2aand a second sub gear134b2b. As the first and second sub gears134b2a,134b2bare sequentially rotated in an engaged state, a rotational force of the first gear portion134b1is transferred to the driving wheel131. In an embodiment, the second gear portion134b2may be formed as a spur gear, a helical gear, and so on.

As aforementioned, the gear unit134bmay be protected from an external environment (e.g., dust) in an accommodated state in the gear box134c. The gear box134cincludes a main case134c1, a middle case134c2and a front case134c3.

The main case134c1is provided with guide holes134c1afor inserting the guide bars135a. A driving motor accommodating portion134c1bfor accommodating the driving motor134atherein is formed at an upper part of the main case134c1. And a first gear accommodating portion134c1cfor accommodating the first gear portion134b1therein is formed on one side surface of the main case134c1. In the drawings, the driving motor134ais accommodated in the driving motor accommodating portion134c1b, and the driving shaft134a1of the driving motor134ais penetratingly-formed in an up and down direction of the main case134c1.

The middle case134c2may be provided between the main case134c1and the front case134c3. More specifically, one side of the middle case134c2may be provided to cover the first gear portion134b1, and another side thereof may be provided to cover the second gear portion134b2.

A first communication hole134c2ais formed at the middle case134c2. More specifically, as a rotation protrusion134b1′ of the first gear portion134b1passes through the first communication hole134c2a, the first gear portion134b1is engaged with the first sub gear134b2aof the second gear portion134b2.

In the drawings, a space for accommodating the second gear portion134b2is formed on one surface of the front case134c3. A second communication hole134c3afor interlocking the second gear portion134b2with the driving wheel131through the front case134c3, is formed at one side of another surface of the front case134c3. And a boss134c3bfor rotatably mounting the driven wheel132is formed at another side thereof.

A protrusion portion134b2b′ is formed at the second sub gear134b2b, and a coupling protrusion134b2b″ engaged with a coupling groove (not shown) of the driving wheel131is formed at the protrusion portion134b2b′. As the protrusion portion134b2b′ passes through the second communication hole134c3aof the front case134c3, the coupling protrusion134b2b″ may be rotatably engaged with the coupling groove (not shown) of the driving wheel131. And the boss134c3bmay be rotatably coupled to a coupling groove (not shown) of the driven wheel132. The front case134c3may further include a foreign material introduction preventing unit134c3cfor preventing introduction of foreign materials by covering at least part of a space defined by the driving wheel131, the driven wheel132and the belt133.

FIG. 12is a view showing a second embodiment of an autonomous cleaner200ofFIG. 3, which illustrates a state that the autonomous cleaner200is positioned on a hard floor. Similar to the first embodiment, the autonomous cleaner200may include a cleaner body210, a cleaning module220, a castor221, a dust container260, etc. Explanations of the components will be replaced by those according to the first embodiment.

Referring toFIG. 12, a driving wheel231is configured to support the cleaner body210together with a driven wheel232. More specifically, the driving wheel231is provided at a front side of the driven wheel232, and the driving wheel231and the driven wheel232are supported on a floor surface. Thus, a caterpillar unit230comes in planar-contact with the floor surface. With such a configuration, the autonomous cleaner200may be stably supported by the caterpillar unit230.

Moreover, even if the castor221is not provided at the cleaning module220, the autonomous cleaner200may be stably supported by the caterpillar unit230. Since the castor221needs not be provided at the cleaning module220, a moving resistance occurring when the autonomous cleaner200moves due to the castor221can be reduced.

FIGS. 13 to 17are views showing a third embodiment of the autonomous cleaner ofFIG. 3, which show a gear unit334band a gear box334cwhich constitute a driving module334.FIG. 13is a view showing a third embodiment of the autonomous cleaner ofFIG. 3, which is a frontal view of a caterpillar unit.FIG. 14is a lateral view of the caterpillar unit shown inFIG. 13.FIG. 15is an exploded perspective view of the caterpillar unit shown inFIG. 13.FIG. 16is a view of the caterpillar unit shown inFIG. 13, which shows components except for wheel-related components. AndFIG. 17is a rear view of the caterpillar unit shown inFIG. 13.

In the drawings, a caterpillar unit330comes in planar-contact with a floor surface, and a driving wheel331and a driven wheel332have the same diameter. However, similar to the first embodiment, as the driving wheel is upward inclined with respect to the driven wheel, a belt333of the caterpillar unit330may come in linear-contact with a floor surface. Further, similar to the second embodiment, as the driving wheel and the driven wheel are provided to support a floor surface, the belt333of the caterpillar unit330may come in planar-contact with the floor surface. Also, similar to the first and second embodiments, the driving wheel331may have a larger diameter than the driven wheel332.

A gear unit (or gear assembly or gear train)334bis formed of a plurality of gears, and transfers a driving force generated from a driving motor334ato the driving wheel331. More specifically, the gear unit334bincludes a first planet gear portion334b1, a second planet gear portion334b2, and a connection gear portion334b3.

The first planet gear portion334b1is engaged with a sun gear to be explained later formed at a driving shaft of the driving motor334a. The second planet gear portion334b2is interlocked with the first planet gear portion334b1. The connection gear portion334b3is interlocked with each of the second planet gear portion334b2and the driving wheel331.

The gear unit334bis accommodated in a gear box334cto be protected from an external environment (e.g., dust). The gear box334cincludes a main case334c1, a middle case334c2, a front case334c3, and a gear cover334c4.

The main case334c1is provided with guide holes334c1afor passing guide bars335atherethrough, at both sides thereof. The driving motor334ais formed at one side of the main case334c1, and the first planet gear portion334b1is accommodated in another side of the main case334c1.

A first communication hole334c1bis formed at the main case334c1such that the driving shaft of the driving motor334ais interlocked with the first planet gear portion334b1through the main case334c1. That is, the driving shaft of the driving motor334ais connected to the first planet gear portion334b1through the first communication hole334c1b. Thus, a driving force provided from the driving motor334ais transferred to the first planet gear portion334b1.

The first planet gear portion334b1includes a first sun gear334b1a, a first ring gear334b1b, a plurality of first planet gears334b1c, and a first cage334b1d. The first sun gear334b1ais coupled to the driving shaft of the driving motor334a, and is exposed to another side of the main case334c1through the first communication hole334c1b. The first sun gear334b1amay be formed to be rotatable in two directions according to a driving signal applied from the controller.

The first ring gear334b1bis formed to enclose the first sun gear334b1aat another side of the main case334c1. The first sun gear334b1ais provided at the center of the first ring gear334b1b. As shown, the first ring gear334b1bmay be formed at the main case334c1.

The plurality of first planet gears334b1care formed to rotate on their axes and to revolve around the first sun gear334b1a, in an engaged state to the first sun gear334b1aand the first ring gear334b1b. In the above structure where the first ring gear334b1bis fixed, a rotation direction of the plurality of first planet gears334b1cis opposite to a rotation direction of the first sun gear334b1a, and a revolving direction of the plurality of first planet gears334b1cis the same as the rotation direction of the first sun gear334b1a.

The first cage334b1drotatably supports a rotation axis of each of the plurality of first planet gears334b1c. The first cage334b1dis provided to cover a part of each of the plurality of first planet gears334b1c. The first cage may be provided to cover the first sun gear334b1a. In this case, the first cage may be configured to rotatably support a rotation shaft of the first sun gear334b1a.

The middle case334c2is coupled to the main case334c1. One side of the middle case334c2is provided to cover the first planet gear portion334b1, and another side of the middle case334c2is formed to accommodate therein the second planet gear portion334b2. A second communication hole334c2afor interlock of the first and second planet gear portions334b1,334b2is formed at the middle case334c2.

The second planet gear portion334b2includes a second sun gear334b2a, a second ring gear334b2b, a plurality of second planet gears334b2c, and a second cage334b2d. The second sun gear334b2ais protruded from the first cage334b1d, and is exposed to another side of the middle case334c2through the second communication hole334c2a.

The second ring gear334b2bis formed to enclose the second sun gear334b2aat another side of the middle case334c2. The second sun gear334b2ais provided at the center of the second ring gear334b2b. As shown, the second ring gear334b2bmay be formed at the middle case334c2.

The plurality of second planet gears334b2care formed to rotate on their axes and to revolve around the second sun gear334b2a, in an engaged state to the second sun gear334b2aand the second ring gear334b2b. In the above structure where the second ring gear334b2bis fixed, a rotation direction of the plurality of second planet gears334b2cis opposite to a rotation direction of the second sun gear334b2a, and a revolving direction of the plurality of second planet gears334b2cis the same as the rotation direction of the second sun gear334b2a.

The second cage334b2drotatably supports a rotation axis of each of the plurality of second planet gears334b2c. The second cage334b2dis provided to cover a part of each of the plurality of second planet gears334b2c. The second cage334b2dmay be provided to cover the second sun gear334b2a. In this case, the second cage may be configured to rotatably support a rotation shaft of the second sun gear334b2a.

The front case334c3is coupled to the main case334c1and the middle case334c2at the housing outside the gear box334c. The second planet gear portion334b2is accommodated into one side of the front case334c3, and the connection gear portion334b3is accommodated into another side thereof. A third communication hole334c3afor interlock of the second planet gear portion334b2with the connection gear portion334b3is formed at the front case334c3.

The connection gear portion334b3includes a first connection gear334b3a, a second connection gear334b3b, and a third connection gear334b3c. The first to third connection gears334b3a,334b3b,334b3care configured to transfer a rotational force of the second planet gear portion334b2to the driving wheel331, in a sequentially engaged state to each other. For instance, the connection gear portion334b3may be formed as a spur gear, a helical gear, and so on.

A protrusion inserted into the third communication hole334c3ais formed at the second cage334b2d. And the protrusion is exposed to another side of the front case334c3through a coupling protrusion engaged with a coupling groove (not shown) of the first connection gear334b3a. First and second boss334c3b,334c3care formed at the front case334c3towards the outside of a cleaner body310, such that the driving wheel331and the driven wheel332are rotatably coupled thereto.

The gear cover334c4is coupled to the front case334c3to cover the connection gear portion334b3. And the gear cover334c4is provided with a fourth communication hole334c4aand a fifth communication hole334c4b, in correspondence to the first and second boss334c3b,334c3c.

The third connection gear334b3cis rotatably coupled to a first boss334c3b. A protrusion334b3c′ is formed at the third connection gear334b3c. And a coupling protrusion334b3c″ engaged with a coupling groove (not shown) of the driving wheel331is formed at the protrusion334b3c′, so as to be exposed to another side of a first cover334c4through the fourth communication hole334c4a. Further, the second boss334c3cis exposed to another side of the fifth communication hole334c4b, in order to be interlocked with the driven wheel332.

A foreign material introduction preventing unit334c4cfor preventing introduction of foreign materials by covering at least part of a space defined by the driving wheel331, the driven wheel332and the belt333may be protruded from the gear cover334c4. In the drawings, the foreign material introduction preventing unit334c4cis arranged to cover a lower space defined by a lower part of the belt333which contacts the driving wheel331, the driven wheel332and a bottom surface. However, the present disclosure is not limited to this. That is, the foreign material introduction preventing unit334c4cmay be arranged to cover up to an upper space defined by an upper part of the belt333, i.e., to cover an entire space.

With such a configuration of the gear unit334band the gear box334c, a driving force formed as a rotation speed and a torque of the driving motor334aare properly changed is transferred to the driving wheel331. And a malfunction of the gear unit334bmay be prevented by the foreign material introduction preventing unit334c4c.

Therefore, a first aspect of the detailed description is to provide an autonomous cleaner having a novel structure capable of maintaining a driving stability and capable of reducing a moving resistance, without the conventional castor provided at a cleaner body in order to support the cleaner body together with caterpillars. A second aspect of the detailed description is to provide an autonomous cleaner capable of controlling a grip force in correspondence to a characteristic of a floor on which the autonomous cleaner is moving. A third aspect of the detailed description is to provide an autonomous cleaner capable of performing the same suspension function regardless of a moving direction.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is provided an autonomous cleaner, comprising: a cleaner body; caterpillar units provided at both sides of the cleaner body, and positioned at a rear side of a cleaning module, wherein the caterpillar unit includes: a driving module; a driving wheel mounted to the driving module, and formed to be rotatable by receiving a driving force from the driving module; a driven wheel mounted to the driving module, and provided at a rear side of the driving wheel; and a belt formed to entirely enclose the driving wheel and the driven wheel as a closed loop, and configured to rotate the driven wheel when the driving wheel is rotated.

In order to achieve the first purpose of the present disclosure, the autonomous cleaner further comprises a cleaning module protruded from one side of the cleaner body, and having a castor. And the cleaner body is supported on a floor surface by the castor and the driven wheel.

The first purpose of the present disclosure may be achieved by a configuration that the cleaner body is supported on a floor surface by the driving wheel and the driven wheel. With the configuration, the cleaner body may be provided with no castor.

The second purpose of the present disclosure may be achieved by a configuration that the driving wheel is provided at a front upper side of the driven wheel, in a state that the cleaner body is supported on a floor surface. The driving wheel may be provided to be higher than the driven wheel by 1°˜5°.

In order to achieve the second purpose of the present disclosure, the caterpillar unit may further include: a housing mounted to the cleaner body, and configured to accommodate the driving module therein; and a suspension formed to be moveable up and down in the housing, configured to guide an up-down movement of the driving module, and configured to absorb an impact when the driving module moves up and down.

In order to achieve the third purpose of the present disclosure, the caterpillar unit may further include: a housing mounted to the cleaner body, and configured to accommodate the driving module therein; and a suspension formed to be moveable up and down in the housing, configured to guide an up-down movement of the driving module, and configured to absorb an impact when the driving module moves up and down.

The suspension may include: guide bars provided in the housing up and down, formed to penetrate the driving module, and configured to guide an up-down movement of the driving module; and an elastic member formed to enclose the guide bars, provided between the housing and the driving module, and configured to absorb an impact when the driving module moves up and down.

The above disclosure may be configured as follows. The driving module may include: a driving motor; a gear unit configured to transfer a rotational force of the driving motor to the driving wheel, after decelerating the driving motor; and a gear box configured to provide a space where the driving motor is mounted, configured to accommodate the gear unit therein, and formed to be moveable up and down in the housing.

A foreign material introduction preventing unit for covering at least part of a space defined by the driving wheel, the driven wheel and the belt may be protruded from the gear box. The driving wheel may have a larger diameter than the driven wheel such that an ascending resistance may become smaller when the autonomous cleaner moves forward than when the autonomous cleaner moves backward. The driving wheel and the driven wheel may have the same diameter such that the autonomous cleaner may have the same ascending performance when moving forward and backward.

The present disclosure may have the following advantages. Firstly, the cleaner body is supported on a floor surface by the castor and the driven wheel, or is supported on a floor surface by the driving wheel and the driven wheel of the caterpillar unit. Accordingly, the conventional castor for stably supporting the cleaner body is not required. Since such a castor serving as a moving resistance when the autonomous cleaner moves on a soft carpet or ascends an obstacle is not installed, a moving performance of the autonomous cleaner may be enhanced.

Secondly, in case of a hard floor (e.g., a bare floor or a papered floor), the cleaner body is supported by the castor of the cleaning module protruded from one side of the cleaner body, and the driven wheel of the caterpillar unit provided at a rear side of the cleaning module. In this case, the driving wheel is provided at a front upper side of the driven wheel, in a spaced state from the floor. On the other hand, in case of a soft floor such as a carpet, even the driving wheel is configured to contact the carpet.

Under the above structure, in a general driving situation (e.g., in case of a hard floor), only the driven wheel of the caterpillar unit comes in linear-contact with the floor, a moving resistance may be reduced. On the other hand, in a situation requiring a high grip force (e.g., in case of a soft floor), even the driving wheel contacts the floor for the same effect as a planar contact. This may enhance a moving performance.

Further, the driving module having the driving wheel and the driven wheel is formed to be moveable up and down, and the suspension is configured to absorb an impact with maintaining a grip force with a floor surface, when the driving module moves up and down. This may allow the grip force to be controlled in correspondence to a characteristic of the floor.

Thirdly, the driving module having the driving wheel and the driven wheel is formed to be moveable up and down along the guide bars, and the elastic member is configured to absorb an impact when the driving module moves up and down. This may allow a ground contact function and an impact attenuation function to be uniformly performed regardless of a moving direction.