Drive unit for a floor robot

Abstract

Drive unit (210) for a floor robot (100), the drive unit (210) comprises the following: - a chain drive (335) with a first sprocket (340) located at the front in the direction of travel and a second sprocket (345) over which a chain (350) runs, wherein the second sprocket (345) is driveable; and - a driven drive wheel (330), wherein a lower end of the drive wheel (330) is lower than a lower end of the chain (350), so that the chain (350) engages in a flat surface (305) only when the drive wheel (330) sinks into the surface (305), - wherein the axles of the sprockets (340, 345) are attached to a rocker arm (310) which can be extended downwards about a pivot axis (315), wherein the rocker arm (310) is pivotable about the pivot axis (315) and the pivot axis (315) is closer to the axis of the first sprocket (340) than to the axis of the second sprocket (345); and - wherein a lower end of the first sprocket (340) is higher than a lower end of the second sprocket (345) and a section of the chain (350) which is stretched between the two sprockets (340, 345) on a side facing the ground (305) forms a load-bearing section which forms an angle with the flat ground (305), this angle being increased when the swing arm (310) rebounds downwards about the axis of rotation (315).

Description

[0001] The present invention relates to a drive unit for a floor robot. In particular, the invention relates to a drive unit for a cleaning robot in a household.

[0002] A robotic vacuum cleaner is designed to move autonomously across a floor surface and clean it. It includes a suction unit and a drive unit. A control unit uses a number of sensors to scan the robot's surroundings and guide it across the floor. Robotic vacuum cleaners are particularly suitable for use in households.

[0003] Different floor coverings, objects lying on the floor such as carpets, cables, or furniture, or structural features like door thresholds or uneven surfaces can place high demands on the flexibility of the drive system. Typically, the drive system comprises two drive wheels, each powered by its own electric motor. The drive wheels are mounted on the right and left sides of the robotic vacuum cleaner, with support wheels optionally provided in front of and behind them. Preferably, each drive wheel can be individually extended from the device, allowing it to maintain contact with the floor if the device encounters an obstacle with its front or rear edge.

[0004] On certain surfaces, such as a deep-pile carpet, one of the drive wheels can lose traction, making the robotic vacuum cleaner difficult to control or, in the worst case, causing it to get stuck. To improve traction, a tracked drive has been proposed. This consists of a front and a rear sprocket over which a chain, usually made of plastic, runs. The contact area on the floor can be larger, thus improving lateral guidance and traction. However, robotic vacuum cleaners with tracked drives may be less maneuverable, noisier during operation, and have higher energy consumption. This can also reduce the robotic vacuum cleaner's operating range.

[0005] Drive units that have both a chain drive and a drive wheel are known in the following context: DE 10 2016 202 878 A1 shows a drive unit whose chain is designed for climbing stairs or curbs. The chain and drive unit are mounted at a fixed angle on a bracket. On a flat surface, the chain lies parallel to it.

[0006] US 6,408,964 B1 shows drive units with chains, each stretched around two sprockets, between which no fixed height relationship is specified and which are arranged on either side of a central axis of rotation. Both sprockets, as well as larger diameter wheels adjacent to them laterally, can pivot freely around the central axis of rotation of the chain drive, depending on the gradient of the ground. This central axis of rotation is arranged symmetrically between the two wheel axles and is connected to a shock absorber.

[0007] US 10 272 961 B2 discloses a drive unit for a ground robot, comprising a chain circulating around two sprockets and, to the side, a drive wheel with a larger diameter than that of the sprockets. The entire drive unit is pivotable about the axis of the drive wheel and the coaxial sprocket, and the respective angular position about this axis of rotation is actively and precisely adjustable, but fixed and unchangeable in each setting; at least until the angular position is changed again.

[0008] DE 331 993 A shows a drive unit with a chain circulating around three sprockets; in addition to the middle and rear sprockets, drive sprockets with a larger diameter than these sprockets are also provided. A rigid, curved section of chain projects forward in front of the actual vehicle and extends from the middle sprocket to the foremost sprocket. The foremost sprocket does not, incidentally, bear any of the vehicle's weight.

[0009] One of the objectives of the present invention is to provide an improved drive unit for a floor robot which achieves an improved temporal profile of the strength of the traction when transitioning from a hard floor to a softer floor on a flat surface, where the traction normally deteriorates or at least changes.

[0010] In particular, the task is to increase traction during this transition, especially on softer ground, to meter this increase and / or to achieve this metering automatically, without requiring active measures on the drive unit or on a floor robot equipped with it.

[0011] The invention solves this problem by means of the subject matter of claims 1 and 11. Dependent claims describe preferred embodiments.

[0012] According to the invention, a drive unit for a floor robot is proposed, wherein the drive unit comprises the following: - a chain drive with a first sprocket located at the front in the direction of travel and a second sprocket over which a chain runs, the second sprocket being driveable; and - a driven drive wheel, wherein a lower end of the drive wheel is lower than a lower end of the chain, so that the chain engages in a level surface only when the drive wheel sinks into the surface, - wherein the axles of the sprockets are attached to a swing arm that can be extended downwards about a pivot axis, the swing arm being pivotable about the pivot axis and the pivot axis being closer to the axle of the first sprocket than to the axle of the second sprocket; and - wherein a lower end of the first sprocket is higher than a lower end of the second sprocket and a section of the chain stretched between the two sprockets on a side facing the ground forms a load run forming an angle with the flat ground, this angle being increased as the swingarm rebounds downwards about the axis of rotation.

[0013] According to a first aspect of the present invention, a drive unit for a floor robot comprises a chain drive with a first and a second sprocket over which a chain runs; and a drive wheel, wherein the second sprocket and the drive wheel are each driveable. The lower end of the drive wheel is positioned lower than the lower end of the chain, so that the chain engages with a level surface only when the drive wheel sinks into the surface.

[0014] According to the invention, the distance between a surface and the lower end of the drive wheel is smaller than the distance between the surface and the lower end of the chain. When the drive unit travels on a flat, hard surface, such as screed, parquet, or linoleum, only the drive wheel makes contact with the surface. This results in low energy consumption, low noise emissions, and high maneuverability. On a soft surface, such as a medium- or long-pile carpet, the drive wheel can sink in slightly, allowing the chain to make contact with the surface. This increased contact area improves the traction of the drive unit on the surface. In this way, the drive mode best suited to the specific surface can be automatically activated.Whether only the drive wheel or also the chain makes contact with the floor on a short-pile carpet can be determined by the difference in height between the lower ends of the drive wheel and the second sprocket. For a typical household, gaps of approximately 1 to 10 mm have proven advantageous.

[0015] The floor robot is preferably designed for use in a household. It should be noted that the chain is typically jointless and may include a toothed belt. The toothed belt may have recesses on its inner side, facing the sprockets, for positive engagement. On its outer side, the toothed belt may be profiled or unprofiled. In yet another embodiment, the positive engagement on the inner side can be replaced by friction; in this case, the chain and sprockets have no engagement elements but simply rest against each other and transmit force in the longitudinal direction of the chain via friction.

[0016] It is further provided that the lower end of the first sprocket is positioned higher than the lower end of the second sprocket, with the first sprocket being located at the front in the direction of travel. According to the invention, a section of the chain, which is tensioned between the sprockets on the side facing the ground, forms a load-bearing section, with an angle existing between a flat surface and the load-bearing section; this angle can be approximately 5°. The deeper the drive sprocket sinks into the ground, the larger the section of the load-bearing section that can transmit traction to the ground can be. The effect of the chain on the ground can thus be gradually improved, depending on the degree of sinkage. This also prevents carpet fringes or carpet fibers from being drawn into the chain drive.

[0017] The drive sprocket has a larger radius than the second sprocket, including the chain. This makes it easier to position the drive sprocket and the second sprocket relative to each other. Furthermore, the larger radius of the drive sprocket can improve the climbing ability of the drive unit, especially if the drive sprocket is not positioned behind the second sprocket.

[0018] The second sprocket and the drive sprocket can be mounted coaxially. In particular, the second sprocket and the drive sprocket can be mounted on a common axle or shaft. This allows for a more compact drive unit design.

[0019] The drive unit can also include a device for interrupting the drive torque to the second sprocket. In one variant, the second sprocket can be coupled to or disconnected from the drive wheel via a clutch. In another variant, the second sprocket can have its own drive. In both variants, the chain drive can be switched off while the ground robot is driven by the drive wheel. The chain drive can be selectively engaged if, for example, it has been determined that the drive wheel cannot provide optimal power transmission to the ground. The non-rotating chain drive does not consume unnecessary energy, allowing the ground robot to travel faster or farther based on a predetermined energy budget.

[0020] The first sprocket can have a smaller radius than the second sprocket. This allows for a more compact and improved design of the drive unit. Furthermore, the sprockets can be more easily positioned so that the load-bearing section maintains the predetermined angle to the ground as described herein.

[0021] According to the invention, the swing arm is not only pivotable around the axis of rotation, but can also be springed out around this axis of rotation in the direction of the ground, so that the angle of rotation or pivoting can itself be changed by the spring.

[0022] As mentioned above, the axles of the sprockets are mounted on a support, the support being pivotable about an axis of rotation that is closer to the axle of the first sprocket than to the axle of the second sprocket. In particular, the axis of rotation and the axle of the second sprocket can be located on opposite sides of the axle of the first sprocket. According to the invention, the swing arm forms the support; specifically, a swing arm extending from the front.

[0023] In a further embodiment, a third sprocket can be provided, positioned opposite the first sprocket with respect to the second. The chain can run over the sprockets in a triangular pattern. The load-bearing section can be positioned between the second sprocket and either the first or third sprocket located in the direction of travel. The angle described here between the load-bearing section and the ground can therefore be achieved in both forward and reverse travel.

[0024] In a further preferred embodiment, an elastic element is provided to pivot and / or rebound the rocker arm downwards. In particular, the rocker arm, i.e., the support, can be pivoted downwards around the axis of rotation from the ground robot towards the ground. If the ground robot traverses an obstacle or step, this pivoting action can ensure improved contact between the drive wheel or track and the ground. The ground robot's ability to traverse or climb over obstacles can thus be enhanced. The preload and stiffness of the elastic element can be predetermined based on the weight of the ground robot, such that a specific distance is maintained between the underside of the ground robot and the ground. The elastic element can, for example, comprise a cylindrical spring, a coil spring, or a torsion bar.In another embodiment, an elastomer can also be used as an elastic element, for example in the form of an elastic cushion.

[0025] The running surfaces of the drive wheel and the chain can be designed according to the different conditions under which they are to transmit traction to the ground.

[0026] Preferably, it can also be provided that the pivot axis of the swing arm is attached to a bearing block.

[0027] Furthermore, the track surface of the chain can be softer than the running surface of the drive sprocket. The softer track surface can provide good traction on soft ground, while the harder running surface of the drive sprocket can promote low energy consumption, high maneuverability, or low noise emissions when driving on hard surfaces. The track surfaces can each be made of, for example, plastic or rubber. The running surface of the drive sprocket can be made of a different material than a rim, wheel disc, or hub. The chain can also comprise different materials, for example, a tensile-strength material that can be coated on one side with a material for the running surface. Alternatively, the chain can also be made entirely of a single material.

[0028] The profile of a track's running surface can be coarser and / or deeper than the profile of a drive wheel's running surface. The track profile can, for example, include protruding material blocks or indentations in the running surface material. The drive wheel is preferably also profiled to minimize slippage on a smooth, level surface. This allows for more precise control of the ground robot. Navigation of the ground robot based on the rotation of the drive wheel can be facilitated.

[0029] According to the invention, a floor robot is further provided, which has the drive unit described herein or two such drive units. Preferably, the floor robot comprises two such drive units, which can be positioned, in particular, on the left and right sides of the floor robot. The drive units can be identical or mirror images of each other. The floor robot can, in particular, be configured to process, preferably clean, a floor surface it traverses. For example, the floor robot can include a vacuuming robot or a mopping robot.

[0030] The invention will now be described in more detail with reference to the accompanying figures, in which: Fig. 1 a floor robot; Fig. 2 a base plate of a floor robot with two drive units; Fig. 3 a side view of a drive unit for a floor robot; Fig. 4 a sectional view of a drive unit for a floor robot; Fig. 5 and Fig. 6 perspective views of a drive unit on a base plate; Fig. 7 and Fig. Show 8 side views of a drive unit on a base plate, each in different positions.

[0031] Fig. Figure 1 shows an exemplary floor robot 100. The floor robot 100 is designed to traverse and process a surface. For this purpose, it comprises a processing unit 105, which in this example includes a bristle roller, and a drive unit 110. The drive unit 110 includes a left and a right floor wheel 115, which are mounted on opposite sides of the floor robot 100. Support wheels 120 can be mounted in front of and behind the floor wheels 115. If the floor robot 100 encounters a raised surface with its chassis or a support wheel 120, the floor wheels 115 can automatically rebound due to an elastic mounting.

[0032] Fig. Figure 2 shows a base plate 205 of a floor robot 100 with a left and a right drive unit 210. The drive units 210 can together form a drive assembly 110. Each drive unit 210 can replace a floor wheel 115 and an associated drive on the floor robot 100. The drive units 210 shown are mirror images of each other; however, in another embodiment, identically constructed drive units 210 can also be used on different lateral sides of a floor robot 100. Preferably, the drive units 210 are each designed as separately manageable units so that they can be easily mounted on the floor robot 205 and removed as needed, for example, for maintenance.

[0033] For easier connection with other figures shown herein, a preferred direction of travel 215 is indicated, which corresponds to a forward movement of the ground robot 100. Regarding the embodiment of Fig. 1 The processing unit 105 can be located in front of the drive units 210 in the direction of travel.

[0034] Fig. Figure 3 shows a side view of a drive unit 210 for a floor robot 100. The example shown is purely illustrative. Fig. The drive unit 210 shown on the right is illustrated. The preferred direction of travel 215 is from right to left.

[0035] The drive unit 210 rests on a surface 305, which in this case is flat and hard. The drive unit 210 comprises a support or rocker arm 310, which is rotatable about a pivot axis 315 that extends horizontally transversely to the direction of travel 215. The pivot axis 315 can be attached to a bearing block 320, which may be connected to the base plate 205 of the floor robot 100. An elastic element 325 exerts a torque about the pivot axis 315 to deflect the rocker arm 310 towards the surface 305. The elastic element 325 is preferably designed as a cylindrical spring, in particular as a tension spring, as shown.

[0036] A drive wheel 330 and a track drive or chain drive 335 are mounted on the swing arm 310. The chain drive 335 comprises a first sprocket 340, a second sprocket 345, and a chain 350 that runs over the first and second sprockets 340 and 345. The drive wheel 330, the first sprocket 340, and the second sprocket 345 are each rotatably mounted relative to the swing arm 310. The drive wheel 330 and the second sprocket 345 are mounted such that the lowest point of the chain 350 has a predetermined distance to the ground 305 when the drive wheel 330 rests on the ground 305 without sinking into it. In the illustrated embodiment, this distance is approximately 1.5 mm.

[0037] To achieve this spacing, the drive wheel 330 and the second sprocket 345 are mounted coaxially on the swingarm 310, with one radius of the drive wheel 330 being larger than the radius of the sprocket 345 including the chain 350 running on it. The difference in radii can correspond to the height difference between the lowest points of the drive wheel 330 and the chain 350 on the second sprocket 345. The first sprocket 340 preferably has a smaller radius than the second sprocket 345 and is further preferably mounted on the swingarm 310 such that its lowest point is a predetermined amount higher than the lowest point of the second sprocket 345. This allows the lowest point of the chain 350 on the first sprocket 340 to be higher than the lowest point on the second sprocket 345.

[0038] In other words, one chain run of the chain 350, which connects the lowest points of the sprockets 340 and 345, can enclose a predetermined angle with the ground 305. This angle is approximately 5° in this case. As will be shown in more detail later, this angle can be increased if the swing arm 310 extends downwards about the pivot axis 315, so that the chain drive 335 and the drive wheel 330 are moved clockwise about the pivot axis 315.

[0039] A drive motor 355, which acts on the drive wheel 330, can also be mounted on the swing arm 310. According to the invention, the second sprocket 345 can be driven, for which purpose it can be connected to the drive wheel 330 in a rotationally stable manner. In a further embodiment, a controllable clutch 360 can be provided to establish or interrupt a torque connection between the drive wheel 330 and the second sprocket 345. In yet another embodiment, a dedicated additional drive motor 355, which acts on the second sprocket 345, can be provided. Power transmission between the drive motor 355 and the drive wheel 330 can be effected by means of a transmission 365, which can be designed, in particular, as a spur gear transmission and can be provided on or in the swing arm 310.

[0040] Fig. Figure 4 shows a sectional view of a drive unit 210 for a floor robot 100. The illustration is based on the in Fig. The embodiment shown in Figure 3 is the basis. The direction of travel 215 extends away from the viewer into the plane of the drawing. In the right-hand area, an enlarged section is shown, which is marked with a circle in the left-hand area.

[0041] In the illustrated embodiment, a drive shaft of the gearbox 365 is supported on one side relative to the rocker arm 310. The second sprocket 345 is torque-fitted onto the drive shaft. Another torque-fit connection holds the wheel 330 to the second sprocket 345. A positive-locking or friction-locking connection can be provided between the gearbox 365 and the second sprocket 345, as well as between the second sprocket 345 and the wheel 330. The positive-locking connection can be implemented in the form of interlocking polygons, and the friction-locking connection in the form of a fit.

[0042] In the selected embodiment, the drive wheel 330 comprises a tire 405, which is mounted radially on the outside to form a running surface of the drive wheel 330. The tire 405 can, for example, be injection-molded, glued, shrunk-on, or held in place on the rest of the drive wheel 330 by clamping force. The tire 405 can be profiled on a radial outer surface and, in this case, includes a circumferential central groove.

[0043] The chain 350 is shown here as an example of a one-piece design and comprises a radially inner profile for engagement with the sprockets 340, 345, and a running surface for engagement with the substrate 305. The running surface may also have a profile.

[0044] As can be seen particularly well in the magnified view, the drive unit 210 is initially supported against the surface 305 only by means of the drive wheel 330. Only when this sinks into the surface 305, the surface 305 has a corresponding unevenness, or the drive wheel 330 is sufficiently deformed by vertical load, does the chain 350 of the chain drive 335 engage with the surface 305. Engagement can also be achieved by applying a load from above to the floor robot 100, causing the rocker arm 310 to compress until the chain 350 at the first sprocket 340 is as low as the lowest point of the drive wheel 330.

[0045] Fig. 5 and Fig. Figure 6 shows perspective views of a drive unit 210 on a base plate 205 of a floor robot 100. The base plate 205 includes a recess through which a section of the drive unit 210 protrudes downwards. Without weight loading, the elastic element 325 pivots the rocker arm 310, so that an enlarged section of the drive unit 210 protrudes through the recess.

[0046] It can be seen that the tire 405 of the drive wheel 330 has an axially split profile. The first sprocket 340 can include one or two axial thrust washers that bear axially against the outside of the chain 350 to prevent the chain 350 from slipping off the first sprocket 340. One or more thrust washers can also be provided on the second sprocket 340. Preferably, the drive wheel 330 is designed such that it prevents the chain 350 from slipping towards the drive wheel 330, so that a separate thrust washer on the second sprocket 340 is not required on this axial side.

[0047] Fig. 7 and Fig. Figure 8 shows side views of a drive unit 210 on a base plate 205 of a floor robot 100, each in different positions. With reference to Fig. 2 shows Fig. 7 a left drive unit 210 and Fig.8 a right drive unit 210. In both representations, a direction of travel 215 runs from right to left.

[0048] In both figures, the drive unit 210 is shown in three different positions relative to the base plate 205. These different positions are reached by varying degrees of spring extension around the axis of rotation 315. When the floor robot 100 is completely lifted from the surface 305, the drive unit 210 pivots fully outwards. The fully compressed position can be reached when the floor robot 100 is on a level surface 305 with its maximum payload.

[0049] It can be seen that the load-bearing section of the chain 350 assumes different angles to a surface 305 or the base plate 205, depending on the degree of compression or rebound of the swing arm 310. The further the swing arm 310 is extended, the greater this angle, which can also be referred to as the angle of attack, can be. The greater the angle of attack, the larger a step or other object can be that the floor robot 100 can overcome. In particular, the chain 350 on the load-bearing section can be automatically positioned against the obstacle when the floor robot 100, with its chassis, such as the base plate 205 or a front support wheel 120, encounters the obstacle. This allows the obstacle to be overcome automatically and more efficiently. Reference sign 100 floor robots 105 Processing equipment 110 Drive unit 115 Ground wheel 120 support wheel 205 Base plate 210 Drive unit 215 Direction of travel 305 Subsurface 310 swing arm 315 Rotary axis 320 bearing block 325 elastic element 330 drive wheel 335 chain drive 340 first sprocket 345 second sprocket 350 chain 355 Drive motor 360 clutch 365 transmission 405 tires

Claims

[1] Drive unit (210) for a floor robot (100), the drive unit (210) comprises the following: - a chain drive (335) with a first sprocket (340) located at the front in the direction of travel and a second sprocket (345) over which a chain (350) runs, wherein the second sprocket (345) is driveable; and - a driven drive wheel (330), wherein a lower end of the drive wheel (330) is lower than a lower end of the chain (350), so that the chain (350) engages in a flat surface (305) only when the drive wheel (330) sinks into the surface (305), - wherein the axles of the sprockets (340, 345) are attached to a rocker arm (310) which can be extended downwards about a pivot axis (315), wherein the rocker arm (310) is pivotable about the pivot axis (315) and the pivot axis (315) is closer to the axis of the first sprocket (340) than to the axis of the second sprocket (345); and - wherein a lower end of the first sprocket (340) is higher than a lower end of the second sprocket (345) and a section of the chain (350) which is stretched between the two sprockets (340, 345) on a side facing the ground (305) forms a load-bearing section which forms an angle with the flat ground (305), this angle being increased when the swing arm (310) rebounds downwards about the axis of rotation (315). [2] Drive unit (210) according to claim 1, wherein the height difference between the lower end of the drive wheel (330) and the lower end of the second sprocket (345) is between one millimeter and ten millimeters. [3] Drive unit (210) according to claim 1 or 2, wherein a radius of the drive wheel (330) is larger than a radius of the second sprocket (345) including the chain (350). [4] Drive unit (210) according to one of the preceding claims, wherein the second sprocket (345) and the drive wheel (330) are mounted coaxially. [5] Drive unit (210) according to one of the preceding claims, further comprising a device for interrupting a drive torque to the second sprocket (345). [6] Drive unit (210) according to one of the preceding claims, wherein the first sprocket (340) has a smaller radius than the second sprocket (345). [7] Drive unit (210) according to one of the preceding claims, further comprising an elastic element (325) to pivot the rocker arm (310) downwards and / or to rebound it. [8] Drive unit (210) according to one of the preceding claims, wherein the axis of rotation (315) is attached to a bearing block (320). [9] Drive unit (210) according to one of the preceding claims, wherein a running surface of the chain (350) is softer than a running surface of the drive wheel (330). [10] Drive unit (210) according to one of the preceding claims, wherein a profile of a running surface of the chain (350) is coarser and / or deeper than a profile of a running surface of the drive wheel (330). [11] Ground robot (100) comprising a drive unit (210) according to one of the preceding claims or two drive units (210) according to one of the preceding claims. [12] Ground robot (100) according to claim 11, wherein the ground robot (100) - a mopping robot, - a robot vacuum cleaner or - another robot for processing and / or cleaning different floor coverings or substrates of a floor surface.

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