Patent Publication Number: US-2023146907-A1

Title: Robot cleaner

Description:
TECHNICAL FIELD 
     The present disclosure relates to a robot cleaner capable of actively moving regardless of a floor surface change with a great height difference. 
     BACKGROUND ART 
     A robot cleaner performs a vacuum cleaning function of sucking dust and foreign materials on a floor or a mopping function of mopping a floor while autonomously traveling in a certain area. 
     The robot cleaner generally includes a rechargeable battery and an obstacle detection sensor configured to avoid an obstacle during traveling to perform cleaning while autonomously traveling. 
     A cleaning nozzle used in the robot cleaner or a vacuum cleaner is adhered to a floor surface to suck foreign materials on a floor in a traveling path into the cleaning nozzle. 
     However, in a case of a cleaning nozzle in the related art, while a robot cleaner is traveling in different floor environments, a phenomenon in which a nozzle unit is caught on a boundary line between a hard floor and a soft floor (e.g., a carpet, a rug, etc.) due to a height difference between the soft and hard floors may occur. 
     In addition, when a robot cleaner travels on a carpet, etc., as great resistance may occur due to friction between the carpet and a brush, problems such that a driving load and a load on a driving motor configured to drive the brush increase, and allowable cleaning time decreases due to an increase in power consumption of the driving motor of the brush occurs. 
     To solve these problems, a suction structure of a robot cleaner is disclosed in KR 10-2017-0099627 A (published in Sep. 1, 2017: hereinafter, referred to as a patent document 1). 
     The robot cleaner disclosed in the patent document 1 includes a suction unit configured to suck foreign materials according to rotation of a brush, and a support portion provided to protrude from a side of the suction unit and configured to support the suction unit to ascend or descend. 
     However, the support portion disclosed in the patent document 1 is provided on a lower surface of a cleaner body and arranged to adhere to a floor surface. Thus, a problem such that foreign materials on the floor surface may be caught in the support portion is present. 
     In addition, WO 2016/032257 A I (published on Mar. 3, 2016; hereinafter, referred to as a patent document 2) discloses a suction nozzle, a robot cleaner, and a method of controlling the same. 
     The robot cleaner disclosed in the patent document 2 is installed in a lower portion of a main body to be movable in an upward/downward direction to move upwardly or downwardly along a surface to be cleaned, and includes a suction nozzle configured to use a main brush to sweep and suck free particles present in the surface to be cleaned. 
     However, in the patent document 2, a connection part connects the suction nozzle to a cleaner body such that the suction nozzle may move relative to the cleaner body in an upward/downward direction, and as the connection part is located in a lower portion of the cleaner body, a problem such that foreign materials on a floor surface may be caught in the connection part is present. 
     In addition, U.S. Pat. No. 7,448,113 B2 (published on Nov. 11, 2008: patent document 3) discloses an autonomous traveling robot cleaner. 
     A cleaning head disclosed in the patent document 3 includes a deck rotatably hinged to a housing. The deck accommodating a brush is raised relative to the housing by a deck adjusting assembly, according to an increase in a torque of the brush. 
     However, in a case of the deck adjusting assembly disclosed in patent document 3, a problem such that a structure of a link connecting the deck to the housing is very complicated is present. 
     In addition, U.S. Pat. No. 8,881,339 B2 (published on Nov. 11, 2014: patent document 4) discloses a robot cleaner. 
     A cleaning assembly (a cleaning head) disclosed in the patent document 4 is configured to be raised from a cleaning surface by a link when the robot cleaner moves from a hard surface to a compressible surface. 
     However, in the patent document 4, a problem such that a link connecting the cleaning assembly to a main body has a complicated structure is present. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     Therefore, to obviate those problems, an aspect of the detailed description is to provide a robot cleaner including a cleaning nozzle such that travel performance may be improved and allowable cleaning time may be extended by reducing a load on a brush driving part, by minimizing a phenomenon in which the cleaning nozzle is caught on a compressible floor surface when a traveling location changes from a hard floor to a compressible floor. 
     Another aspect of the detailed description is to provide a robot cleaner including a cleaning nozzle such that introduction of foreign materials may be minimized by using a link for an ascending/descending operation of the cleaning nozzle, and a simple structure is provided. 
     Another aspect of the detailed description is to provide a robot cleaner including a cleaning nozzle such that twisting is prevented during vertical ascending/descending of the cleaning nozzle. 
     Another aspect of the detailed description is to provide a robot cleaner including a cleaning nozzle such that a shape of a flow path may be constantly maintained during ascending/descending of the cleaning nozzle even when a suction flow path connected between the cleaning nozzle and a cleaner body is moving. 
     Solution to Problem 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a robot cleaner including: a cleaner body equipped with a control unit and a driving wheel of which driving is controlled by the control unit; a cleaning nozzle mounted inside an opening portion opening downwardly in a lower portion of the cleaner body, and configured to ascend or descend relative to the cleaner body according to changes in a height of a cleaning surface on which the cleaner body travels; a plurality of ascending/descending guides included in the cleaning nozzle and configured to guide the ascending or the descending of the cleaning nozzle; and a plurality of support portions included in the cleaner body and configured to support the plurality of ascending/descending guides, respectively, so that the plurality of ascending/descending guides pass through the plurality of support portions, respectively, and move in an upward or downward direction. 
     In this configuration, the cleaning nozzle rises relative to the cleaner body upon being pressed due to a height of a compressible floor surface such as a carpet, thus solving a problem of the cleaning nozzle being caught on a cleaning surface, and enhancing travel performance. 
     The robot cleaner may further include catching hooks provided to protrude from upper end portions of the plurality of ascending/descending guides, respectively, and be caught on the plurality of support portions, respectively, when a plurality of ascending/descending guides descend such that the cleaning nozzle is hung onto an upper portion of the cleaner body. 
     In this configuration, the ascending/descending guides may be configured to guide the ascending or the descending of the cleaning nozzle, and accommodated in the cleaner body and supported in a form of being hung onto an upper portion in the cleaner body. Thus, introduction of dust, foreign materials, etc. may be minimized and a simple structure of the ascending/descending guides may be provided. 
     The robot cleaner may further include: a plurality of auxiliary ascending/descending guides included in the cleaning nozzle to be arranged below the plurality of ascending/descending guides, and configured to guide vertical ascending or descending of the cleaning nozzle; and a plurality of guide accommodation units included in the cleaner body, be in face-contact with both side surfaces of the plurality of auxiliary ascending/descending guides, and configured to guide vertical ascending or descending of the plurality of auxiliary ascending/descending guides. 
     In this configuration, the auxiliary ascending/descending guides may guide an ascending or descending operation of the cleaning nozzle vertically to prevent twisting during the ascending or the descending of the cleaning nozzle. 
     The cleaning nozzle may include a brush accommodation unit configured to accommodate a brush module, and the plurality of auxiliary ascending/descending guides may be provided to protrude from an upper portion of the brush accommodation unit. 
     The cleaning nozzle may include a brush module, and the plurality of ascending/descending guides may be provided protrude from front and rear portions of the cleaning nozzle in an upward direction, respectively, with the brush module interposed therebetween. 
     The cleaning nozzle may include: a nozzle base including a suction inlet communicating with the opening portion, and including shaft support portions at both ends of the nozzle base, respectively, wherein the shaft support portions rotatably support a brush module exposed via the suction inlet in a downward direction; and a nozzle cover coupled to an upper portion of the nozzle base to cover the brush module. 
     The nozzle cover may include: a brush accommodation unit configured to cover and accommodate the brush module in a circumferential direction; and a flange unit extending along an edge of the brush accommodating unit and coupled to the nozzle base, wherein the plurality of ascending/descending guides are provided to protrude from an upper surface of the flange unit, and arranged spaced apart from each other in a forward/backward direction of the brush accommodation unit. 
     The plurality of ascending/descending guides may be provided at left and right sides of the cleaning nozzle, respectively, and configured to guide end portions of the left and right sides of the cleaning nozzle to independently ascend or descend. 
     The robot cleaner may further include a nozzle accommodation unit installed in the cleaner body to cover the cleaning nozzle and configured to accommodate the cleaning nozzle, wherein the plurality of support portions are provided in the nozzle accommodation unit to be penetrated in an upward/downward direction so that the plurality of support portions are penetrated by the plurality of ascending/descending guides in an upward direction, respectively. 
     The nozzle cover may include: a brush accommodation unit configured to cover and accommodate the brush module in a circumferential direction; a flange unit extending along an edge of the brush accommodating unit and coupled to the nozzle base; and auxiliary ascending/descending guides arranged below the plurality of ascending/descending guides, respectively, provided to protrude from a front surface of the flange unit, and configured to guide vertical ascending or descending of the cleaning nozzle. 
     The robot cleaner may further include a nozzle accommodation unit installed in the cleaner body to cover the cleaning nozzle and configured to accommodate the cleaning nozzle, wherein the guide accommodation units include guide grooves into which the plurality of auxiliary ascending/descending guides slide, and are provided to protrude from the nozzle accommodation unit, respectively, to cover the plurality of auxiliary ascending/descending guides. 
     The cleaning nozzle may include a brush module configured to sweep away foreign materials on the cleaning surface via the opening portion; a suction guide mounted to be inclined downwardly in a lower portion of the nozzle base, and configured to receive and raise foreign materials swept away by the brush module; and a suction guide holder coupled to a lower portion of the nozzle base to fix the suction guide, with the suction guide arranged between the lower portion of the nozzle base and the suction guide holder. 
     The robot cleaner may further includes: a nozzle accommodation unit installed in the cleaner body to cover the cleaning nozzle; a discharge outlet provided in a rear portion of the cleaning nozzle and configured to discharge foreign materials sucked via the opening portion; a communication part provided in a rear portion of the nozzle accommodation unit to communicate with the discharge outlet; and a suction flow path part configured to communicate the discharge outlet to the communication part, and including an elastic material to elastically support the cleaning nozzle so that the cleaning nozzle may ascend or descend. 
     In this configuration, the suction flow path may include an elastic material, so that a shape of a flow path may be constantly maintained during ascending/descending of the cleaning nozzle even when a suction flow path connected between the cleaning nozzle and the cleaner body is moving. 
     When the cleaning nozzle rises due to a height of the cleaning surface, the suction flow path part may elastically press the cleaning nozzle to an original position of the cleaning nozzle. 
     The suction flow path part may further include a fastening flange provided to protrude from an end portion of the suction flow path part in an outward direction along a circumferential direction and fastened to the communication part, wherein the suction flow path part extends to protrude toward a rear direction from the discharge outlet. 
     The cleaning nozzle may include: a brush accommodation unit configured to accommodate a brush module configured to sweep away foreign materials on the cleaning surface via the opening portion; and a brush driving part mounted in an end portion of one side of the brush accommodation unit, and configured to rotate the brush module. 
     The robot cleaner may further include a nozzle accommodation unit installed in the cleaner body to cover the cleaning nozzle and configured to accommodate the cleaning nozzle, wherein the nozzle accommodation unit further includes a through-portion penetrated by the brush driving part so that the brush driving part protruding from an end portion of the brush accommodation unit toward outside of the nozzle accommodation unit may ascend or descend with the cleaning nozzle. 
     The cleaning nozzle may include a suction flow path part extending to protrude from a discharge outlet of the brush accommodation unit in a rear direction to discharge the foreign materials, and configured to elastically support the cleaning nozzle to correct an asymmetric load on the brush driving part. 
     The suction flow path part may be provided in a form of a closed loop. 
     The suction flow path part may include an elastic material, and may further include a reinforcement portion provided such that a thickness is further increased along an inner circumference of a section of the suction flow path part, the section being close to the brush driving part. 
     The suction flow path part may include an elastic material, and may further include a plurality of reinforcement ribs arranged spaced apart from each other along a surface of an outer circumference of a section of the suction flow path part, the section being close to the brush driving part, and provided to protrude in an outward direction. 
     There is also provided a robot cleaner including: a cleaner body equipped with a control unit and a driving wheel of which driving is controlled by the control unit; a cleaning nozzle mounted inside an opening portion opening downwardly in a lower portion of the cleaner body, and configured to ascend or descend relative to the cleaner body according to changes in a height of a cleaning surface on which the cleaner body travels; a nozzle accommodation unit installed in the cleaner body to cover an upper portion of the cleaning nozzle; a brush module mounted to be accommodated in the cleaning nozzle; a brush driving part mounted in an end portion of one side of the cleaning nozzle and configured to drive the brush module; and a suction flow path part connecting the cleaning nozzle to the nozzle accommodation unit to suck foreign materials swept away by the brush module, and configured to elastically support the cleaning nozzle to ascend or descend and correct an asymmetric load on the brush driving part. 
     Advantageous Effects of Invention 
     Hereinafter, effects of a robot cleaner according to the present disclosure will be described. 
     In accordance with the detailed description, a plurality of ascending/descending guides may be provided in an upper portion of a cleaning nozzle to protrude in an upward direction. A plurality of support portions may be provided on an upper portion of a nozzle accommodation unit to be penetrated therethrough, the nozzle accommodation unit being configured to cover the upper portion of the cleaning nozzle. The ascending/descending guides pass through the support portions to be supported by the support portions to ascend or descend. Thus, the cleaning nozzle may ascend or descend from an opening portion opening downwardly in a low portion of the cleaner body, according to a height difference between floors. Accordingly, when a cleaner body moves from a hard floor surface to a compressible floor surface, a phenomenon in which the cleaning nozzle is caught on the compressible floor surface is minimized, and thus, travel performance may be improved. In addition, as a brush in a brush module rotates in a state of rising above the compressible floor surface, rotation resistance of the brush module may be reduced, and thus, a load on a brush driving part may be reduced. Power consumption of the brush driving part may be reduced, and thus, allowable cleaning time may be extended. 
     In addition, as catching hooks are provided to protrude from upper end portions of the ascending/descending guides and be caught on support portions, the cleaning nozzle may be supported in a state of being hung onto the upper portion of a nozzle accommodation unit in the cleaner body. Accordingly, the catching hooks may limit a lowest descending height of the cleaning nozzle. 
     Further, auxiliary ascending/descending guides may be provided to protrude from front and rear surfaces of the cleaning nozzle, respectively, to be arranged below the ascending/descending guides. The guide accommodation units may be provided to protrude from front and rear surface of the nozzle accommodation unit, respectively, in an outward direction, to be arranged below the support portions. The auxiliary ascending/descending guides may be slidably supported in an upward/downward direction along the guide grooves provided inside the guide accommodation unit. Accordingly, the auxiliary ascending/descending guides may slide upwardly or downwardly in a state of being accommodated in the guide accommodation unit, and thus, may stably support vertical ascending/descending of the cleaning nozzle. In addition, the auxiliary ascending/descending guides and the guide accommodation unit may prevent twisting during vertical ascending/descending of the cleaning nozzle. 
     Further, an upper end portion of the guide accommodation unit is provided to have a closed structure in which upper ends of the guide grooves are closed. Thus, when upper end portions of the auxiliary ascending/descending guides receive pressing force and rise due to a height of a floor, a maximum ascending height of the auxiliary ascending/descending guides may be limited due to the closed structure of the guide accommodation unit. 
     The ascending/descending guides and the auxiliary ascending/descending guides, each configured to guide an ascending/descending operation of the cleaning nozzle, may be arranged on an upper portion of the brush accommodation unit arranged in an upper inner portion of the cleaner body to minimize introduction of foreign materials. In addition, the support portions and the guide accommodation unit, each being configured to support the ascending/descending guides and the auxiliary ascending/descending guides to move upwardly or downwardly, have simple structures, respectively, and thus, may greatly contribute to miniaturization of the robot cleaner and cost reduction. 
     Additionally, the suction flow path part, configured to suck foreign materials, etc. swept away by the brush module, may extend to protrude from a rear portion of the cleaning nozzle to connect to the nozzle accommodation unit. The suction flow path part includes an elastic material, and may elastically support the cleaning nozzle configured to ascend/descend according to a height of a floor. 
     In addition, the brush driving part may be mounted in an end portion at one side of the cleaning nozzle to drive the brush module accommodated in the cleaning nozzle. The suction flow path part may further include the reinforcement portion configured to increase a thickness along a circumference of the suction flow path part located close to the brush driving part or constituting the protruding portions. Thus, an asymmetric load on the brush driving part may be corrected. 
    
    
     
       BRIEF DESCRIPTION OF DARWINIGS 
         FIG.  1    is a perspective view illustrating a state in which a cleaning nozzle assembly is mounted inside a robot cleaner according to the present disclosure. 
         FIG.  2    is a conceptual view illustrating a state in which the cleaning nozzle assembly of  FIG.  1    is disassembled. 
         FIG.  3    is a rear perspective view illustrating the cleaning nozzle assembly of  FIG.  1    viewed from a rear direction. 
         FIG.  4    is an exploded view illustrating a state in which the cleaning nozzle assembly of  FIG.  3    is disassembled. 
         FIG.  5    is a conceptual view illustrating a cleaning nozzle of  FIG.  4    viewed from a rear direction. 
         FIG.  6    is a cross-sectional view of  FIG.  5    taken along a line VI-VI. 
         FIG.  7    is a cross-sectional view of  FIG.  6    taken along a line VII-VII. 
         FIG.  8    is a conceptual view illustrating a position of an ascending/descending guide when the robot cleaner in the present disclosure travels on a hard floor. 
         FIG.  9    is a conceptual view illustrating a position of the ascending/descending guide when the robot cleaner in the present disclosure travels on a compressible floor such as a carpet. 
         FIG.  10    is a conceptual view illustrating a cleaning nozzle according to another embodiment of the present disclosure. 
         FIG.  11    is a cross-sectional view of  FIG.  10    taken along a line XI-XI. 
         FIG.  12    is a conceptual view illustrating another aspect of a suction flow path part according to the present disclosure. 
         FIG.  13    is a conceptual view illustrating another aspect of the cleaning nozzle according to the present disclosure. 
     
    
    
     MODE FOR THE INVENTION 
     Hereinafter, embodiments disclosed herein will be described in detail with reference to the accompanying drawings, and the same or similar elements are designated with the same numeral references, regardless of the numerals in the drawings, and their redundant description will be omitted. In general, a suffix such as “module” and “unit” may be used to refer to elements or components. Use of such a suffix herein is merely intended to facilitate description of the specification, and the suffix itself is not intended to give any special meaning or function. In describing the present disclosure, if a detailed explanation for a related known technology or construction is considered to unnecessarily divert the gist of the present disclosure, such explanation has been omitted but would be understood by those skilled in the art. The accompanying drawings are used to help easily understand the technical idea of the present disclosure and it should be understood that the idea of the present disclosure is to not limited by the accompanying drawings. The idea of the present disclosure should be construed to extend to any alterations, equivalents and substitutes besides the accompanying drawings. 
     It will be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another. 
     It will be understood that when an element is referred to as being “connected with” another element, the element can be connected with the another element or intervening elements may also be present. In contrast, when an element is referred to as being “directly connected with” another element, there are no intervening elements present. 
     A singular representation may include a plural representation unless it represents a definitely different meaning from the context. 
     Terms such as “include” or “has” are used herein and should be understood that they are intended to indicate an existence of several components, functions or steps, disclosed in the specification, and it is also understood that greater or fewer components, functions, or steps may likewise be utilized. 
       FIG.  1    is a perspective view illustrating a state in which an assembly of a cleaning nozzle  110  is mounted inside a robot cleaner according to the present disclosure. 
       FIG.  2    is a conceptual view illustrating a state in which the assembly of the cleaning nozzle  110  of  FIG.  1    is disassembled. 
       FIG.  3    is a rear perspective view illustrating the assembly of the cleaning nozzle  110  of  FIG.  1    viewed from a rear direction. 
       FIG.  4    is an exploded view illustrating a state in which the assembly of the cleaning nozzle  110  of  FIG.  3    is disassembled. 
       FIG.  5    is a conceptual view illustrating a state in which the cleaning nozzle  110  of  FIG.  4    is viewed from a rear direction. 
       FIG.  6    is a cross-sectional view of  FIG.  5    taken along a line VI-VI. 
       FIG.  7    is a cross-sectional view of  FIG.  6    taken along a line VII-VII. 
     The robot cleaner is configured to perform a function of cleaning a floor while autonomously traveling in a certain area. Here, the cleaning of the floor may be understood as including suctioning foreign materials and dust on the floor or mopping the floor. 
     In this example, the robot cleaner is configured to perform a vacuum cleaning function of, while autonomously traveling in a certain area, sucking air from the floor and collecting dust by separating the dust with foreign materials from the sucked air. 
     The robot cleaner is configured to include a cleaner body  100 . The cleaner body  100  provides an appearance of the robot cleaner. Various components including a control unit configured to control the robot cleaner are equipped with or mounted in the cleaner body  100 . 
     In the cleaner body  100 , a circuit substrate (not shown) constituting the control unit may be arranged. Various modules, for example, a brush module  123  or a mop module (not shown) may be detachably coupled to the cleaner body  100 . 
     Driving wheels  101  (refer to  FIG.  13   ) are provided on a lower surface of the cleaner body  100 . The driving wheels  101  are configured to rotate by receiving driving power from a wheel driving motor  1011 . A wheel driving motor  1011  may receive a control signal from the control unit to control driving of the wheel driving motor  1011 . 
     The driving wheels  101  may be provided at both left and right sides on the lower surface of the cleaner body  100 , respectively. The wheel driving motor  1011  may be connected to each of the driving wheels  101  for independent driving of each of the driving wheels  101 . 
     The cleaner body  100  may move in a left, right, forward, or backward direction or rotate according to rotation of the driving wheels  101 . 
     Auxiliary wheels  1012  (refer to  FIG.  13   ) may be further provided on the lower surface of the cleaner body  100 . The auxiliary wheels  1012  may be distinguished from the driving wheels  101  in that the auxiliary wheels  1012  only have a function of rolling on a floor. 
     The auxiliary wheels  1012  may support the cleaner body  100  together with the driving wheels  101 . The auxiliary wheels  1012  are configured to assist in traveling of the cleaner body  100 . 
     A plurality of the auxiliary wheels  1012  may be rotatably installed at respective centers of a front portion and a rear portion of the cleaner body  100  with reference to a center line in a side direction passing centers of a plurality of the driving wheels  101 . 
     A battery (not shown) configured to supply power to the robot cleaner is mounted in the cleaner body  100 . The battery may be configured to be rechargeable, and may be detachably attached to a lower surface portion of the cleaner body  100 . 
     A sensing unit (not shown) may be arranged in a front portion of the cleaner body  100 . The sensing unit may be positioned at a constant height from a front surface of the cleaner body  100 . 
     The sensing unit may be configured to detect an obstacle, a geographic feature, etc. in front of the cleaner body  100  so that the cleaner body  100  does not collide with the obstacle. 
     When the robot cleaner is configured to perform a vacuum cleaning function, air including dust and foreign materials may be sucked through an opening portion  102  provided in the lower portion of the cleaner body  100 . 
     The opening portion  102  may be provided to extend along a left/right direction with reference to a traveling direction of the cleaner body  100 . The opening portion  102  may be provided to have a rectangular shape. The opening portion  102  may be provided to pass through the lower surface of the cleaner body  100  in an upward/downward direction. 
     A cleaning nozzle  110  configured to clean dust and foreign materials on a floor surface is provided inside the opening portion  102 . 
     A nozzle accommodation unit  104  is provided in the opening portion  102  of the cleaner body  100 . The nozzle accommodation unit  104  is mounted on the lower surface of the cleaner body  100  to cover the opening portion  102 . The nozzle accommodation unit  104  may extend in a left/right direction with reference to the traveling direction of the cleaner body  100 . 
     The nozzle accommodation unit  104  includes an accommodation space therein to accommodate the cleaning nozzle  110 . A lower portion of the nozzle accommodation unit  104  is provided to open in a downward direction. The nozzle accommodation unit  104  is configured to cover an upper portion of the cleaning nozzle  110 . 
     A plurality of bosses  103  may be arranged spaced apart from each other in a forward/backward direction and a left/right direction along a circumference of the opening portion  102  to fasten the nozzle accommodation unit  104  to the cleaner body  100 . The plurality of bosses  103  may be provided in a cylindrical form to protrude in an upward direction. 
     Fastening grooves may be provided inside the plurality of bosses  103 , respectively. 
     A plurality of fastening units  1041  may be arranged on a front end surface and a rear end surface of the nozzle accommodation unit  104 , respectively, to be spaced apart from each other in a left/right longitudinal direction and protrude in a forward/backward direction. The fastening grooves may be provided inside the fastening units  1041 . 
     Fastening members such as a screw pass through the fastening units  1041  to be fastened to the plurality of bosses  103  to thereby fasten the nozzle accommodation unit  104  to the cleaner body  100 . 
     The cleaning nozzle  110  is configured to accommodate a brush module  123  therein. The cleaning nozzle  110  may be configured to include a nozzle cover  111  and a nozzle base  116 . 
     The nozzle cover  111  may include a brush accommodation unit  112  and a flange unit  114 . 
     The brush accommodation unit  112  may be provided to have an empty cylindrical form. The brush accommodation unit  112  includes an accommodation space therein to accommodate the brush module  123 . A cylindrical structure of the brush accommodation unit  112  may minimize flow resistance of air sucked into the brush accommodation unit  112 . 
     The brush module  123  includes a brush attached to an outer circumferential surface of a brush body having a cylindrical form and is configured to rotate the brush to sweep dust and foreign materials away from the floor. 
     A bottom portion of the brush accommodation unit  112  is open to expose the brush module  123  toward a floor surface through the bottom portion of the brush module  123 . The brush module  123  may be rotatably mounted inside the cleaning nozzle  110 . 
     A rotation shaft is provided to protrude at both ends of the brush module  123  in a direction of a shaft, and the brush module  123  is configured to rotate with reference to the rotation shaft. 
     A brush driving part  124  is mounted at an end of one side of the brush accommodation unit  112 . The brush driving part  124  may include a brush motor  125  configured to drive the brush module  123 , and a gear box  126  configured to deliver power of the brush motor  125  to the brush module  123 . 
     The gear box  126  may include a plurality of gears therein. The gear box  126  may be configured to connect the brush motor  125  to the brush module  123 . 
     The gear box  126  is arranged on a side surface of an end of the brush accommodation unit  112 , and a side of the gear box  126  may be coupled to the rotation shaft of the brush module  123  to deliver power. The rotation shaft of the brush module  123  may pass through the end of the brush accommodation unit  112  to couple to the brush module  123 . 
     The brush driving part  124  may be configured to protrude toward an outside of the nozzle accommodation unit  104 . A through-portion  104  may be provided at one side of the nozzle accommodation unit  104  to be penetrated therethrough in an upward/downward direction. The nozzle accommodation unit  104  may be penetrated by the brush driving part  124  via the through-portion  108 . 
     In this configuration, the brush driving part  124  may be equipped in one end portion of the cleaning nozzle  110 , and pass through the through-portion  108  in the nozzle accommodation unit  104  to ascend or descend together with the cleaning nozzle  110 . 
     The brush module  123  may rotate by receiving power from the brush driving part  124  to sweep dust and foreign materials away from the floor. 
     The dust and foreign materials in the air sucked through the brush module  123  are filtered and collected in a dust container  127 . The air separated from the dust and foreign materials is discharged to outside of the cleaner body  100 . 
     A suction flow path part  136  and an exhaust flow path (not shown) may be provided inside the cleaner body  100 , the suction flow path part  136  being configured to guide air introduced via the opening portion  102  to the dust container  127 , and the exhaust flow path being configured to guide flow of the air from the dust container  127  to outside of the cleaner body  100 . 
     The suction flow path part  136  may extend to protrude from a rear portion of the brush accommodation unit  112  toward the dust container  127 . The suction flow path part  136  may be connected to communicate with an inlet provided on a front surface of the dust container  127 . 
     The dust container  127  may be detachably accommodated inside the cleaner body  100 . 
     The dust container  127  may be provided with at least one of a filter and a cyclone for filtering the dust and foreign materials in the sucked air. 
     A flange unit  114  is provided in a lower end portion of the brush accommodation unit  112 . The flange unit  114  is provided to protrude toward an outward direction along a circumference of a lower end of the brush accommodation unit  112 . The flange unit  114  may be provided to have a rectangular shape. 
     A nozzle base  116  may be provided to correspond to the opening portion  102 . The nozzle base  116  may be slightly smaller than the opening portion  102 . 
     The nozzle base  116  may be configured to be fastened to a lower portion of the nozzle cover  111 . The nozzle base  116  may be fastened to the flange unit  114 . The nozzle base  116  may be arranged to overlap the flange unit  114  in an upward/downward direction. 
     The nozzle base  116  may be provided to have a closed-loop rectangular shape. 
     A suction inlet  121  may be provided in the nozzle base  116 . The suction inlet  121  may be provided to communicate with the opening portion  102 . Air outside a periphery of a cleaning surface on which the cleaner body  110  travels may be sucked into the brush accommodation unit  112  via the suction inlet  121 . 
     A plurality of shaft support portions  112  may be provided to axially protrude from end portions of both sides of the nozzle base  116  in a longitudinal direction. 
     A plurality of shaft support portions  122  may be configured to support the rotation shaft protruding from both ends of the brush module  123 . Both end portions of the rotation shaft may be rotatably supported by bearings, respectively. The shaft support portions  122  may be provided to have a form of a curved surface concavely in a downward direction. 
     A height of a front portion of the nozzle base  116  may be less than a height of a rear portion of the nozzle base  116 . 
     A plurality of inclined surfaces may be provided in left and right side surface portions of the nozzle base  116 . The inclined surfaces may be provided to be inclined downwardly from a front side surface portion to a rear side surface portion of the nozzle base  116 . The inclined surfaces may be provided below the shaft support portions  122 . 
     A lower end of a front portion of the nozzle base  116  and a lower end of the rear portion of the nozzle base  116 , having a height difference therebetween, may be connected to each other by the inclined surfaces. 
     The rear portion of the nozzle base  116  may adhere to a floor surface, and a gap may be provided between a lower end of the front portion of the nozzle base  116  and the floor surface. 
     In this configuration, even when the rear portion of the nozzle base  116  adheres to the floor surface, air outside the front portion of the cleaner body  110  may be smoothly sucked into the suction inlet  121  via the gap. 
     To fasten the nozzle cover  111  to the nozzle base  116 , a plurality of fastening projections  117  may be provided to protrude from a front surface of the front portion and a rear surface of the rear portion of the nozzle base  116  in a forward-backward direction. 
     Each of the fastening projections  117  may be provided to have a rectangular shape extending in a longitudinal direction of the nozzle base  116 . The fastening projections  117  may be arranged spaced apart from each other in a left/right longitudinal direction of the nozzle base  116 . 
     A plurality of fastening holes  115  may be provided in a front portion and a rear portion of the flange unit  114  to be penetrated through in a forward/backward direction. The plurality of fastening holes  115  may be provided to correspond to the plurality of fastening projections  117 , respectively, so that the fastening projections  117  may match the fastening holes  115 . 
     The fastening projections  117  may be provided to have a wedge form to be downwardly inclined in a forward/backward direction. Accordingly, when the nozzle base  116  is inserted into the flange unit  114 , the fastening projections  117  may be easily assembled into the fastening holes. 
     A suction guide  134  may be mounted in a lower portion of the nozzle base  116 . 
     The suction guide  134  functions as a dustpan configured to support and raise foreign materials swept away by the brush module  123  into the brush accommodation unit  112 . 
     The suction guide  134  may be arranged in a rear portion of the nozzle base  116 . 
     The suction guide  134  may be provided to extend in a left/right direction of the nozzle base  116  and have a form of a flat plate with a small thickness. 
     A front end portion of the suction guide  134  is provided to be inclined to be positioned at a lower height compared to a position of a rear end portion of the suction guide  134 . This is to keep the front end portion of the suction guide  134  close to the floor surface as possible to thereby push and raise the front end portion above inside of the suction inlet  121 . 
     A part of the suction guide  134  may be mounted into the nozzle base  116  to protrude in a downward direction via the suction inlet  121  of the nozzle base  116 . 
     A fixing portion  1341  may be provided in a rear end portion of the suction guide  134  to protrude in a rear direction. The fixing portion  1341  may extend horizontally in a longitudinal direction of the suction guide  134 . 
     A plurality of fitting holes  1342  may be provided in the fixing portion  1341  to be penetrated therethrough in an upward/downward direction. The fitting holes  1342  may be arranged spaced apart from each other in a longitudinal direction of the fixing portion  1341 . The fitting holes  1342  may have a narrow width and be provided to extend in a direction in which the fixing portion  1341  extends. 
     A protruding end portion  1343  may be provided on a lower surface of the suction guide  134  to protrude in a downward direction. The protruding end portion  1343  may extend in a longitudinal direction of the suction guide  134 . 
     A suction guide holder  135  is included inside the nozzle base  116  to fix the suction guide  134  to a rear portion inside the nozzle base  116 . 
     The suction guide holder  135  may include a front holder portion  1351  and a rear holder portion  1353 . 
     The front holder portion  1351  and the rear holder portion  1353  may have a certain angle therebetween and extend in a left/right side direction to have a length corresponding to the suction guide  134 . 
     The front holder portion  1351  may be inclined downwardly from a front end portion of the rear holder portion  1353  to a rear end portion of the suction guide  134 , and have a form of a curved surface. 
     The front holder portion  1351  may be arranged between a lower end of the brush accommodation unit  112  and a rear end of the suction guide  134 . The brush accommodation unit  112 , the front holder portion  1351 , and the suction guide  134  may be arranged to overlap each other in a circumferential direction, and have a cross-sectional shape of one circular arc. 
     In this configuration, foreign materials swept away by the brush module  123  may be smoothly raised over inside of the suction inlet  121  along the suction guide  134  and the front holder portion  1351  without being caught. 
     A plurality of fixing holes  118  may be provided in a rear portion of the nozzle base  116  to be penetrated therethrough in an upward/downward direction. The fixing holes  118  may be arranged spaced apart from each other in a left/right side direction of the nozzle base  116 . Each of the fixing holes  118  may be provided to have a narrow width and have a length extending in the left-right side direction. 
     A plurality of fixing projections  1352  may be provided to protrude from a lower surface of the front holder portion  1351  in a downward direction. The fixing projections  1352  may be arranged spaced apart from each other in a left/right side direction of the front holder portion  1351 . 
     The rear holder portion  1353  may be arranged to overlap a part of the rear portion of the nozzle base  116 , in which the fixing holes  118  are provided, in an upward/downward direction. 
     The fixing projections  1352 , the fitting holes  1342 , and the fixing holes  118  may be arranged to overlap each other in an upward/downward direction. 
     The fixing projections  1352  are fit and coupled to the fitting holes  1342  and the fixing holes  118  by penetrating therethrough. Thus, the front holder portion  1351  may push the fixing portion  1341  in the suction guide  134  in a downward direction to fix the fixing portion  1341  to the nozzle base  116 . 
     A catching jaw  1211  may be provided at a rear end of the opening portion  102  of the nozzle base  116 . The catching jaw  1211  may be arranged in front of the fixing holes  118 . The catching jaw  1211  may constitute the rear end of the opening portion  102  and be arranged to have a vertical height along an upward direction. 
     A protruding end portion  1343  of the suction guide  134  is arranged on a front surface of the catching jaw  1211  to be in face contact with the front surface of the catching jaw  1211  to prevent a front end portion of the suction guide  134  from rotating in a downward direction or the fixing portion  1341  from being raised in an upward direction. 
     When, via the fitting holes  1342  and the fixing holes  118 , the fixing projections  1352  are fit and coupled thereto, the fixing portion  1341  may be stably seated in and fixed to an inner side surface of the nozzle base  116 . 
     The rear holder portion  1353  may be extend horizontally from a rear end the front holder portion  1351  to a rear direction. 
     A plurality of coupling holes  1354  may be provided to be penetrated therethrough in an upward/downward direction to fasten the rear holder portion  1353  to a rear portion of the nozzle base  116 . The coupling holes  1354  may be arranged spaced apart from each other in a longitudinal direction of the rear holder portion  1353 . 
     A plurality of coupling bosses  119  may be provided to protrude from the inner side surface of the nozzle base  116  in an upward direction to fasten the rear holder portion  1353  to the nozzle base  116 . The coupling bosses  119  may be arranged spaced apart from each other in a longitudinal direction of the nozzle base  116 . 
     The coupling holes  1354  and the coupling bosses  119  are arranged to overlap each other in an upward/downward direction. 
     A coupling member such as a screw passes through the coupling holes and is screw-fastened into a fastening groove provided in the coupling bosses  119  to fasten a rear holder portion  1353  to the nozzle base  116 . 
     In this configuration, the suction guide holder  135  may securely fasten the suction guide  134  to the rear portion inside the nozzle base  116  using the fixing projections  1352  and the fixing holes  118 . 
     In a state when the suction guide  134  is mounted in the suction inlet  121  of the nozzle base  116 , the suction guide holder  135  may be fastened to the inside of the suction inlet  121  to thereby support the suction guide  134 . 
     A plurality of correct position guides  120  may be configured to guide the suction guide holder  135  to a correct position in the nozzle base  116 , and provided to protrude from the rear portion inside the nozzle base  116  in an upward direction. 
     The correct position guides  120  may be provided to have a structure in which a front portion and left and right sides are closed and a rear portion is open, that is, in a form of “E.” 
     A plurality of correct guide accommodation holes  1355  may be provided to be penetrated therethrough in an upward/downward direction to accommodate the correct position guides  120  on a lower surface of the rear holder portion  1353 . 
     The correct position guide accommodation holes  1355  and the correct position guides  120  may be arranged to overlap each other in an upward/downward direction. 
     As the correct position guides  120  are inserted into and match the correct position guide accommodation holes  1355 , the coupling holes  1354  in the rear holder portion  1353  and the coupling bosses  119  in the nozzle base  116  may be provided to overlap each other in an upward/downward direction to thereby improve assembling property. 
     The cleaning nozzle  110  may be mounted to ascend or descend relative to the cleaner body  100 , according to changes in a height of a floor while traveling from a hard floor  1  to a compressible floor such as a carpet  10 , etc. 
     The cleaning nozzle  110  may perform an ascending or descending operation between a first position and a second position. 
     The first position is an initial position, and the initial position of the cleaning nozzle  110  may be set to fit the hard floor  1 . 
     The second position is located higher than the first position. The second position is a position to which the cleaning nozzle  110  ascends according to a height of the compressible floor when the cleaner body  100  travels on the compressible floor such as the carpet  10 , etc. 
     The cleaning nozzle  110  may be supported by a plurality of ascending/descending guides  128  and a plurality of support portions  130  to ascend or descend in a form of being hung onto an upper inner portion of the cleaner body  100 . 
     For example, the cleaning nozzle  110  may be supported to ascend or descend in a form of being hung onto an upper portion of the nozzle cover  111 . 
     The ascending/descending guides  128  may be provided to protrude from an upper portion of the brush accommodation unit  112  in an upward direction. 
     The ascending/descending guides  128  may be arranged spaced apart from each other in a longitudinal direction of the brush accommodation unit  112 . 
     The ascending/descending guides  128  may be provided to have a rectangular shape having a narrow width and a height in a vertical direction greater than the width. The ascending/descending guides  128  may have a shape of a thin plate and extend in a forward/backward direction of the brush accommodation unit  112 . 
     Each of the ascending/descending guides  128  may extend upwardly or downwardly in a vertical direction. 
     A thickness of the ascending/descending guides  128  may be provided to be smaller than a height of the ascending/descending guides  128  in the vertical direction and a width of the ascending/descending guides  128  in the left/right side direction. 
     The support portions  130  are provided in an upper portion of the nozzle accommodation unit  104 . The support portions  130  may be provided in the upper portion of the nozzle accommodation unit  104  to be respectively penetrated therethrough in an upward/downward direction. The support portions  130  may be arranged to overlap the ascending/descending guides  128  in a protruding direction of the ascending/descending guides  128 . 
     The support portions  130  may be provided to have a shape identical to that of the ascending/descending guides  128  to cover left, right, front, rear, and side surfaces of the ascending/descending guides  128 . 
     The ascending/descending guides  128  may pass through the support portions  130  to be supported by the support portions  130  to move in an upward/downward direction. 
     A catching hook  129  is provided on an upper end portion of the ascending/descending guides  128  to protrude in an outward direction. The catching hook  129  is provided such that the upper end portion of the ascending/descending guides  128  is caught on the upper portion of the nozzle accommodation unit  104 . 
     The catching hook  129  is provided to be caught on the support portions  130 . 
     In this configuration, the ascending/descending guides  128  may pass through the support portions  130  to ascend from the first position (the initial position) to the second position (an ascended position). In this case, the support portions  130  guide ascending and descending operations of the ascending/descending guides  128 . 
     In addition, when the ascending/descending guides  128  descend from the second position (the ascended position) to the first position (the initial position), the catching hook  129  are caught on the support portions  130 . In this case, the catching hook  129  may limit the initial position (a lowest position) of the cleaning nozzle  110 . 
     The support portions  130  may be positioned at an uppermost end of the nozzle accommodation unit  104  in an upward direction from a lower end of the nozzle accommodation unit  104 . 
     However. a position of the support portions  130  is not limited thereto, and may be positioned at a constant height of the nozzle accommodation unit  104  in an upward direction from the lower end of the nozzle accommodation unit  104 . 
     A position of the ascending/descending guides  128  is not limited to the uppermost end of the brush accommodation unit  112 , and may be arranged in front and rear portions of the brush accommodation unit  112 . Alternatively, the ascending/descending guides  128  may be provided on upper front and rear surfaces of the flange unit  114 . 
     A plurality of supports may be provided to protrude in a forward/backward direction from a front portion and a rear portion of the nozzle accommodation unit  104 , respectively. 
     The supports may be provided to protrude from the front portion and the rear portion of the nozzle accommodation unit  104 , respectively. 
     A first support  106  among the supports may protrude toward a front portion of the nozzle accommodation unit  104 . 
     A second support  107  among the supports may protrude toward a rear portion of the nozzle accommodation unit  104 . 
     The first and second supports  106  and  107  may extend toward a left/right side direction of the nozzle accommodation unit  104 . 
     Each of upper surfaces of the first and second supports  106  and  107  may be provided to have a shape of a flat surface at a constant height in an upward direction from a lower end of the nozzle accommodation unit  104 . 
     To assist the ascending and descending operations of the cleaning nozzle  110 , a plurality of auxiliary ascending/descending guides  131  may be included in the flange unit  114 . 
     The auxiliary ascending/descending guides  131  may be provided to protrude from front and rear surfaces of the flange unit  114  in a forward/backward direction, respectively. 
     The auxiliary ascending/descending guides  131  may be arranged spaced apart from each other on front and rear surfaces of the flange unit  114  in a left/right side direction, respectively. 
     The auxiliary ascending/descending guides  131  may protrude vertically in an outward direction relative to front and rear surfaces of the flange unit  114 , respectively. In addition, the auxiliary ascending/descending guides  131  may extend vertically in a direction of a height of the flange unit  114 . 
     A plurality of guide accommodation units  132  may be provided to protrude from a front surface of the first support  106  and a rear surface of the second support  107 , respectively. The guide accommodation units  132  may be arranged spaced apart from each other in a longitudinal direction of the supports. 
     Guide grooves  133  may be provided in the guide accommodation units  132  such that the auxiliary ascending/descending guides  131  may be slidably moved. The guide grooves  133  are provided to cover the auxiliary ascending/descending guides  131 . 
     A vertical height of the guide grooves  133  may be provided to be greater than that of the auxiliary ascending/descending guides  131 . 
     The guide accommodation units  132  may be provided such that upper ends of the guide grooves  133  are closed. 
     A vertical height of the guide grooves  133  may limit a maximum slidable height of the auxiliary ascending/descending guides  131 . 
     A height of the upper ends of the guide grooves  133  may limit a maximum height of the auxiliary ascending/descending guides  131 , as well as a maximum ascendable height of the ascending/descending guides  128  and a maximum ascendable height of the cleaning nozzle  110 . 
     Hereinafter, functions and effects of the ascending/descending guides  128  and the auxiliary ascending/descending guides  131 , each configured to guide ascending and descending operations of the cleaning nozzle  110  according to the present disclosure, are described. 
       FIG.  8    is a conceptual view illustrating a position of the ascending/descending guides  128  when the robot cleaner in the present disclosure travels on the hard floor  1 . 
       FIG.  9    is a conceptual view illustrating a position of the ascending/descending guides  128  when the robot cleaner in the present disclosure travels on a compressible floor such as the carpet  10 , etc. 
     The robot cleaner may travel on the hard floor  1  or the compressible floor such as the carpet  10 , etc. 
     When the robot cleaner travels on the hard floor  1 , the floor  1  pressed by the driving wheels  101  has a same height as that of a cleaning surface cleaned by the cleaning nozzle  110 . 
     However, when the robot cleaner travels on the compressible floor such as the carpet  10 , etc., the compressible floor pressed by the driving wheels  101  has a height different from that of a cleaning surface cleaned by the cleaning nozzle  110 . 
     Since the carpet  10  includes a textile material, as the driving wheels  101  press the carpet  10 , a height of the cleaning surface is greater than that of a floor pressed by the driving wheels  101 . A lower surface of the cleaning nozzle  110  is pressed in an upward direction according to the height of the cleaning surface. 
     When the robot cleaner passes through a boundary line between different floor environments to move from the hard floor  1  to the compressible floor, the cleaning nozzle  110  may rise according to pressing force of the cleaning surface. 
     The ascending/descending guides  128  positioned at an upper end of the nozzle cover  111  or the brush accommodation unit  112  guides an ascending operation of the cleaning nozzle  110 . 
     The ascending/descending guides  128  may protrude and rise by passing through the support portions  130  penetrably provided at an uppermost end of the nozzle accommodation unit  104 . 
     The support portions  130  may allow ascending of the ascending/descending guides  128 , but limit left, right, forward, or backward movement of the ascending/descending guides  128 . 
     Accordingly, the cleaning nozzle  110  may be supported by the ascending/descending guides  128  and the support portions  130  and rise from the initial position (the first position) to the second position that is located higher than the first position. 
     In addition, the auxiliary ascending/descending guides  131  may be provided in a left, right, front, or rear portion of the cleaning nozzle  110 , the nozzle cover  111 , or the flange unit  114  to guide a vertically ascending operation of the cleaning nozzle  110 . 
     The auxiliary ascending/descending guides  131  may be arranged in a position lower than that of the ascending/descending guides  128  and assist the ascending/descending guides  128  in the cleaning nozzle  110 . 
     The auxiliary ascending/descending guides  131  may protrude from front and rear surfaces of the flange unit  114 , and be accommodated in the guide grooves  133  in the guide accommodation units  132  arranged in a left, right, front, or rear portion of the nozzle accommodation unit  104  and slidably arranged in an upward/downward direction to slide upwardly along the guide grooves  133 . 
     The guide accommodation unit  132  is provided to have a vertical height greater than that of the auxiliary ascending/descending guides  131 . As the upper ends of the guide grooves  133  provided in the guide accommodation units  132  are closed, a maximum ascending height of the auxiliary ascending/descending guides  131  may be limited. 
     On the other hand, when the robot cleaner passes through the boundary line between the different floor environments to move from the compressible floor to the hard floor  1 , a height of the cleaning surface becomes same as that of the hard floor  1 . Thus, as the pressing force on the cleaning surface is relieved, the cleaning nozzle  110  may descend to the original position. 
     In this case, as the catching hook  129  provided on the upper end of the ascending/descending guides  128  is caught on the support portions  130 , the cleaning nozzle  110  is supported in a state of being hung onto the uppermost end of the nozzle accommodation unit  104 . Thus, a lowest position of the cleaning nozzle  110  may be constantly maintained. 
       FIG.  10    is a conceptual view illustrating a cleaning nozzle  210  according to another embodiment of the present disclosure. 
       FIG.  11    is a cross-sectional view of  FIG.  10    taken along a line XI-XI. 
     In the present embodiment, a plurality of ascending/descending guides  228  may extend to upwardly protrude from front and rear portions of the cleaning nozzle  210 , respectively. 
     A plurality of support portions  230  may be provided on an upper surface of a nozzle accommodation unit  204  to be penetrated through in an upward/downward direction. The support portions  230  may be arranged spaced apart from each other in a forward/backward direction or a left/right side direction from the upper surface of the nozzle accommodation unit  2044 . 
     The ascending/descending guides  228  may be supported to ascend or descend by passing through the support portions  230 , respectively, to guide the cleaning nozzle  210  to ascend or descend. 
     Catching hooks  229  may be provided to protrude from upper portions of the ascending/descending guides  228  in an outward direction, respectively. The catching hooks  229  may be caught on the support portions  230  to limit a minimum descending height of the ascending/descending guides  228 . The catching hook  229  may be supported in a state when the cleaning nozzle  210  is hung onto the upper side of the nozzle accommodation unit  204  in the cleaner body  100  using the ascending/descending guides  228 . 
     A suction flow path part  236  may be provided to connect a discharge outlet  113  of the cleaning nozzle  210  to a communication part  209  of the nozzle accommodation unit  204 . 
     Fastening flanges  237  may be included at one side and the other side of the suction flow path part  236 , respectively. The fastening flanges  237  may further extend in an outward direction along a circumference of the suction flow path part  236  at both end portions of the suction flow path part  236 . 
     The fastening flanges  237  may have a thickness greater than that of the suction flow path part  236 . 
     A fastening flange  237  provided at one side of the suction flow path part  236  is fastened to the discharge outlet  113  (refer to  FIG.  5   ) of the cleaning nozzle  210 . Another fastening flange  237  provided at the other side of the suction flow path part  236  is fastened to the communication part  209  of the nozzle accommodation unit  204 . 
     A flange fixing slot  1091  may be provided in a periphery of the communication part  209  to fasten the fastening flange  237  to the communication part  209 . The flange fixing slot  1091  (refer to  FIG.  6   ) may have a same shape as that of the fastening flanges  237 . 
     Fixing projections  1371  (refer to  FIG.  6   ) is provided to protrude from outer and inner side ends of the fastening flanges  237 , respectively, and inserted into and combined with the flange fixing slot  1091  (refer to  FIG.  6   ) to be fixed thereto. 
     Alternatively, fastening grooves may be provided concavely along a circumference of the fastening flanges  237  so that the fastening flanges  237  are inserted into and fixed to the discharge outlet  113  (refer to  FIG.  5   ) or the communication part  209 . 
     The suction flow path part  236  includes an elastic material, and may elastically support the cleaning nozzle  210  to ascend when the cleaning nozzle  210  ascends. The suction flow path part  236  may have an adjustable length, and be provided to be stretchable in a foldable form or a form of bellows. 
     The suction flow path part  236  may be provided in a form of a closed loop. The closed loop of the suction flow path part  236  may include a plurality of line portions  2361  arranged spaced apart from each other in a vertical direction and a plurality of curved portions  2362  arranged spaced apart from each other in a left/right side direction to connect the line portions  2361  to each other. 
     The line portions  2361  may be provided in a form of a flat surface. The curved portions  2362  may be provided in a form of a curved surface having a shape of a circular arc. 
     An end portion of the suction flow path part  236  may be connected to communicate with the discharge outlet  113  in the cleaning nozzle  210 . The other end portion of the suction flow path part  236  may be connected to communicate with the communication part  209  in the nozzle accommodation unit  204 . 
     Both of the end portions of the suction flow path part  236  may be fastened to the cleaning nozzle  210  and the nozzle accommodation unit  204 , respectively, and provided to have a great thickness. Fastening grooves may be provided along a circumference of each of the both end portions of the suction flow path part  236 . As the discharge outlet  113  of the cleaning nozzle  210  and the communication part  209  in the nozzle accommodation unit  204  fit into the fastening grooves, the suction flow path part  236  may be securely fastened to the cleaning nozzle  210  and the nozzle accommodation unit  204  to maintain air tightness. 
     The suction flow path part  236  may be configured to correct an asymmetric load on a brush driving part  224  mounted in an end portion at one side of the cleaning nozzle  210 . 
     The suction flow path part  236  may be arranged inclined between a rear surface of the cleaning nozzle  210  and a rear surface of the nozzle accommodation unit  204 . 
     The suction flow path part  236  may be configured to correct an asymmetric load on a brush driving part  224  mounted in the end portion at one side of the cleaning nozzle  210 . 
     To do so, the suction flow path part  236  may include a flow path body and a reinforcement portion  238 . 
     The reinforcement portion  238  may be provided integrally with the suction flow path part  236  and have a same elastic material as that of the suction flow path part  236 . 
     The reinforcement portion  238  may have a great thickness in one section along an inner circumference of the flow path body 
     In a beginning portion in which the reinforcement portion  238  is arranged, an inclination portion may be provided such that a thickness of the reinforcement portion  238  gradually increases. 
     The reinforcement portion  238  may be arranged adjacent to the brush driving part  224 . 
     For example, when the suction flow path part  236  provided in a rear portion of the cleaning nozzle  210  is viewed from a rear direction, the brush driving part  224  may be arranged at a right end portion of the cleaning nozzle  210 . 
     In the reinforcement portion  238 , when two line portions  2361  facing each other in an upward/downward vertical direction of the suction flow path part  236  are divided into three sections, a section corresponding to ⅓ of whole lengths of the two line portions  2361  and arranged toward and adjacent to the brush driving part  224 , and a right portion of the curved line portions  2362  connecting to the section may have a thickness greater than that of the other sections corresponding to ⅔ of the whole lengths of the two line portions  2361  and a left portion of the curved line portions  2362 . 
     In this configuration, a strength at one side of the suction flow path part  236  arranged adjacent to the brush driving part  224  is increased by the reinforcement portion  238 . Thus, the asymmetric load on the brush driving part  224  may be corrected. That is, the reinforcement portion  238  may minimize inclination of one side of the cleaning nozzle  210  in a downward direction compared to the other end of the cleaning nozzle  210  due to the asymmetric load on the brush driving part  224 . 
     A description of other configurations is identical or similar to the embodiments described with reference to  FIGS.  1  to  9   , and thus, will not be provided here. 
       FIG.  12    is a conceptual view illustrating another aspect of the suction flow path part  236  according to the present disclosure. 
     In the present embodiment, the suction flow path part  236  includes a plurality of protruding portions  239  to correct an asymmetric load on the brush driving part  224 . Thus, the suction flow path part  236  in the present embodiment is different from that described with reference to  FIG.  11   . 
     The protruding portions  239  may be provided in one section of an outside circumference of the suction flow path part  236 . The protruding portions  239  may be arranged spaced apart from each other in a right ⅓ section of the line portions  2361  of the suction flow path part  236  to be adjacent to the brush driving part  224 . Spaces between the protruding portions  239  may be provided to be different from each other. 
     For example, spaces between the protruding portions  239  may be narrow when the protruding portions  239  are far apart from the curved line portions  2362 . 
     This is because the line portions  2361  of the suction flow path part  236  are affected by gravity more greatly than by support force of the curved line portions  2362  at a center portion of the line portions  2361  of the suction flow path part  236 , compared to being at the curved line portions  2362 . Thus, by providing many protruding portions  239  in a part of the line portions  2361  far apart from the curved line portions  2362 , a reduction in the support force of the curved line portions  2362  may be compensated for. 
       FIG.  13    is a conceptual view illustrating another aspect of a cleaning nozzle  320  according to the present disclosure. 
     In the present embodiment, a part of the cleaning nozzle  320  protrudes outwardly from a front surface of a cleaner body  300 . Thus, the present embodiment is different from the embodiment described above with reference to  FIGS.  1  to  9   . 
     The cleaner body  300  may be provided to have a cylindrical form. 
     The cleaning nozzle  320  may be configured to protrude from a front surface of the cleaner body  300  in an outward direction. 
     A nozzle accommodation unit  310  configured to accommodate the cleaning nozzle  320  may be provided to protrude from the front surface of the cleaner body  300  in an outward direction. The nozzle accommodation unit  310  may extend to protrude from a lower front portion of the cleaner body  300  in a left/right side direction. 
     A sensing unit  301  may be provided to protrude from an upper front portion of the cleaner body  300  in an outward direction. The sensing unit  301  may be arranged to overlap the cleaning nozzle  320  in an upward/downward direction. 
     The sensing unit  301  may be arranged in an upper portion of the nozzle accommodation unit  310 . 
     The sensing unit  301  is configured to detect an obstacle, a geographic feature, etc. in front of the nozzle accommodation unit  310  so that the nozzle accommodation unit  310  does not collide with the obstacle. The sensing unit  301  may be implemented using an ultrasound sensor, etc. 
     The cleaner body  300  may include a dust container accommodation unit  324 . The dust container accommodation unit  324  may be detachably coupled to a dust container  323  configured to separate and collect dust from sucked air. 
     The dust container accommodation unit  324  may be provided in a rear portion of the cleaner body  300 . The dust container accommodation unit  324  may have a form open toward the rear portion of the cleaner body  300 . The dust container accommodation unit  324  may be provided to recess from the rear portion to a front portion of the cleaner body  300 . 
     A part of the dust container  323  may be accommodated in the dust container accommodation unit  324 , and the other part of the dust container  323  may be provided to protrude toward the rear portion of the cleaner body  300 . 
     A cover of the dust container  323  may be provided in an upper portion of the dust container  323 . A front end portion of the cover of the dust container  323  may be hinged to the dust container accommodation unit  324  in the cleaner body  300  so that a rear end portion of the cover of the dust container  323  may be configured to rotate in an upward/downward direction. 
     When the cover of the dust container  323  is arranged to cover an upper surface of the dust container  323 , the dust container  323  may be prevented from being separated from the cleaner body  300  by the cover of the dust container  323 . 
     The cleaning nozzle  320  is installed to ascend or descend in an upward/downward direction relative to the nozzle accommodation unit  310  in the cleaner body  300 . 
     The cleaning nozzle  320  includes a plurality of ascending/descending guides  321  provided to protrude in an upward direction. 
     The nozzle accommodation unit  310  includes a plurality of support portions  331  configured to support upward/downward movement of the ascending/descending guides  321 . 
     The support portions  331  are provided in front and rear portions of the nozzle accommodation unit  310 , respectively, to be penetrated therethrough in an upward/downward direction so that the support portions  331  are penetrated by the ascending/descending guides  321  and slidably support the ascending/descending guides  321  in an upward/downward direction. 
     A catching hook  322  is provided on an upper end of the ascending/descending guides  321  to protrude in an outward direction. The catching hook  322  is provided to be caught on support portions  311  when the ascending/descending guides  321  are descending. 
     In this configuration, the catching hook  322  may limit a lowest position (an initial position) of the ascending/descending guides  321 . 
     The cleaning nozzle  320  may include the plurality of auxiliary ascending/descending guides  131  (refer to  FIGS.  6  and  7   ). The auxiliary ascending/descending guides  131  (refer to  FIGS.  6  and  7   ) may protrude from the cleaning nozzle  320  in an outward direction. The auxiliary ascending/descending guides  131  may extend vertically in an upward/downward direction. The auxiliary ascending/descending guides  131  may be arranged below the ascending/descending guides  321 . 
     The auxiliary ascending/descending guides  131  may be configured to vertically raise or lower the cleaning nozzle  320 . 
     The nozzle accommodation unit  310  may include the plurality of guide accommodation units  132 . The guide accommodation unit  132  (refer to  FIGS.  6  and  7   ) may include the guide grooves  133  (refer to  FIGS.  6  and  7   ) therein to support the auxiliary ascending/descending guides  131  to slide in an upward/downward direction. The guide accommodation unit  131  may be arranged below the support portions  311 . 
     The ascending/descending guides  321  and the auxiliary ascending/descending guides  131  may be arranged in front and rear portions of the cleaning nozzle  320 , respectively, to have the brush module  123  accommodated in the cleaning nozzle  320  arranged therebetween. 
     The support portions  311  and the guide accommodation unit  132  may be arranged in front and rear portions of the nozzle accommodation unit  310 , respectively, to have the brush module  123  arranged therebetween. 
     Accordingly, according to the present disclosure, the plurality of ascending/descending guides  128 ,  228 , or  321  are provided in an upper portion of the cleaning nozzle  110 ,  210 , or  320  to protrude in an upward direction. The plurality of support portions  130 ,  230 , or  311  are provided on an upper portion of the nozzle accommodation unit  104 ,  204 , or  310  to be penetrated therethrough, the nozzle accommodation unit  104 ,  204 , or  310  being configured to cover the upper portion of the cleaning nozzle  110 ,  210 , or  320 . The ascending/descending guides  128 ,  228 , or  321  pass through the support portions  130 ,  230 , or  311  to be supported by the support portions  130 ,  230 , or  311  to ascend or descend. Thus, the cleaning nozzle  110 ,  210 , or  320  may ascend or descend from the opening portion  102  opening downwardly in a low portion of the cleaner body  300 , according to a height difference between floors. Accordingly, when the cleaner body  300  moves from a surface of the hard floor  1  to a compressible floor surface, a phenomenon in which the cleaning nozzle  110 ,  210 , or  320  is caught on the compressible floor surface is minimized, and thus, travel performance may be improved. In addition, as a brush in the brush module  123  rotates in a state of rising above the compressible floor surface, rotation resistance of the brush module  123  is reduced, and thus, a load on the brush driving part  124  or  224  may be reduced. Power consumption of the brush driving part  124  or  224  may be reduced, and thus, allowable cleaning time may be extended. 
     In addition, as the catching hook  129 ,  229 , or  322  are provided to protrude from upper end portions of the ascending/descending guides  128 ,  228 , or  321  and be caught on the support portions  130 ,  230 , or  311 , the cleaning nozzle  110 ,  210 , or  320  may be supported in a state of being hung onto the upper portion of the nozzle accommodation unit  104 ,  204 , or  310  in the cleaner body  300 . Accordingly, the catching hook  129 ,  229 , or  322  may limit a lowest descending height of the cleaning nozzle  110 ,  210 , or  320 . 
     Further, the auxiliary ascending/descending guides  131  may be provided to protrude from front and rear surfaces of the cleaning nozzle  110 ,  210 , or  320 , respectively, to be arranged below the ascending/descending guides  128 ,  228 , or  321 . The guide accommodation units  132  may be provided to protrude from front and rear surface of the nozzle accommodation unit  104 ,  204 , or  310 , respectively, in an outward direction, to be arranged below the support portions  130 , 230 , 311 . The auxiliary ascending/descending guides  131  may be slidably supported in an upward/downward direction along the guide grooves  133  provided inside the guide accommodation unit  132 . Accordingly, the auxiliary ascending/descending guides  131  may slide upwardly or downwardly in a state of being accommodated in the guide accommodation unit  132  to stably support vertical ascending/descending of the cleaning nozzle  110 ,  210 , or  320 . In addition, the auxiliary ascending/descending guides  131  and the guide accommodation unit  321  may prevent twisting during the vertical ascending/descending of the cleaning nozzle  110 ,  210 , or  320 . 
     Further, an upper end portion of the guide accommodation unit  132  is provided to have a closed structure in which upper ends of the guide grooves  133  are closed. Thus, when upper end portions of the auxiliary ascending/descending guides  131  receive pressing force and rise due to a height of a floor, a maximum ascending height of the auxiliary ascending/descending guides  131  may be limited due to the closed structure of the guide accommodation unit  132 . 
     The ascending/descending guides  128 ,  228 , or  321  and the auxiliary ascending/descending guides  131 , each configured to guide an ascending/descending operation of the cleaning nozzle  110 ,  210 , or  320 , may be arranged on an upper portion of the brush accommodation unit  112  arranged in an upper inner portion of the cleaner body  300  to minimize introduction of foreign materials. In addition, the support portions  130 ,  230 , or  311  and the guide accommodation unit  132  are configured to support the ascending/descending guides  128 ,  228 , or  321  and the auxiliary ascending/descending guides  131  to move upwardly or downwardly and have simple structures, respectively, which will greatly contribute to miniaturization of the robot cleaner and cost reduction. 
     Further, the suction flow path part  236  is configured to suck foreign materials, etc. swept away by the brush module  123 , and extend to protrude from a rear portion of the cleaning nozzle  110 ,  210 , or  320  to connect to the nozzle accommodation unit  104 ,  204 , or  310 . The suction flow path part  236  includes an elastic material, and may elastically support the cleaning nozzle  110 ,  210 , or  320  configured to ascend/descend according to a height of a floor. 
     In addition, the brush driving part  124  or  224  is mounted in an end portion at one side of the cleaning nozzle  110 ,  210 , or  320  to drive the brush module  123  accommodated in the cleaning nozzle  110 ,  210 , or  320 . The suction flow path part  236  may further include the reinforcement portion  238  for increasing a thickness along a circumference of the suction flow path part  236  located close to the brush driving part  124  or  224  or constituting the protruding portions  239 . Thus, an asymmetric load on the brush driving part  124  or  224  may be corrected.