NL2023867B1 - A roller unit for rolling lawns - Google Patents

Abstract

The application describes a roller unit (100) for rolling lawns. The 5 roller unit comprises a frame (102), a driven shaft (104) attached to the frame with bearings (105), and at least one vibrating grass roller (106). Eccentric elements (108) are fixed to the driven shaft (104). Bearings (110) around the eccentric elements mechanically couple the at least one vibrating grass roller to the frame such that when the driven shaft is rotated, the at least one vibrating grass roller 10 makes a vibrating movement relative to the driven shaft with a stroke in any direction in a plane perpendicular to the driven shaft. Fig. 1

Description

A ROLLER UNIT FOR ROLLING LAWNS

TECHNICAL FIELD The subject disclosure relates to a roller unit for rolling lawns.

BACKGROUND ART The rolling of grass fields has been done for many years. A meadow is rolled to roll away unevenness and get a solid surface back. On sports fields, rolling is used to smooth away the unevenness of a sliding, for example.

On golf courses there is an enormous increase in the rolling of grass. Mainly to increase the roll distance of the ball, but also to save on mowing or to insert a product into the turf. Initially, only the green was rolled, but for a number of years now, fairways have been rolled for the same reasons.

For years, simple round (solid) rollers have been pulled over the surface to smooth the surface. Weights are then added to increase the impact. A roller should not be too wide, because then there is a good chance that the roller will not carry and work across the full width. It is better to pull several narrower roller units next to each other over the surface. Furthermore, "Dead" weight often has too little effect if the surface is hard and if the soil is soft, the roller will sink through the turf.

In the past, vibrating rollers were therefore developed, whereby the ground pressure energy no longer came from pure weight, but from a mechanically generated vibratory movement. By changing the rotational speed of an unbalanced weight, the impact on the grass surface could easily be changed (in relation to the driving speed). Such type of grass rollers are disclosed in US3635134A, US5261213A, US6467245B1 and US7588389B1.

In almost all cases, the vibration movement is generated by driving an unbalanced shaft. Depending on the unbalanced weight and shaft speed, the impact on the ground surface can be adjusted. To prevent the entire machine from vibrating, the vibrating roller with unbalanced shaft is often suspended from the main frame in rubbers. The vibratory movements are therefore transmitted indirectly to the turf. Theoretically, a roller with unbalanced shaft can come to a standstill when the surface is hard.

SUMMARY OF INVENTION It is an object of the present technology to provide an improved roller unit for rolling lawns, which overcomes at least one of the disadvantages of the devices described above. According to an aspect of the subject technology, this object is achieved by a roller unit for rolling lawns having the features of claim 1. Advantageous embodiments and further ways of carrying out the present technology may be attained by the measures mentioned in the dependent claims. A roller unit for rolling lawns according to the subject technology comprises a frame, a driven shaft attached to the frame with bearings and at least one vibrating grass roller. Eccentric elements fixed to the driven shaft and bearings around the eccentric elements mechanically couple the at least one vibrating grass roller to the frame. When the driven shaft is rotated, the at least one vibrating grass roller makes a vibrating movement relative to the driven shaft with a stroke in any direction in a plane perpendicular to the driven shaft.

The concept of the present technology is that the frame and the vibrating rollers are actively moved with respect to each other by the eccentric elements. This movement in respect to each other results in a rapidly fluctuating pressure force acting on the lawn surface. This directly applied impact will significantly increase the roller efficiency and make new applications possible. Because the turf is vibrated over a wider area, products such as sand and fertilisers will settle better and faster in the top layer of the turf. The vibration is a movement directly imposed in every direction (up and down, forward and backward), with which the roller(s) is/are actively moved up and down. This active movement compacts the top layer of the turf or other soil layer. The impact is greater than a roller vibrated by a rotating imbalance, because the rotation of the imbalance must be converted into a compression force.

In an embodiment, the vibrating movement has a predefined maximum stroke. This feature defines the maximum local unevenness in the surface that can be caused by the roller when, for example, the roller unit stops driving for a moment.

In an embodiment, the stroke is not related to the rotation speed of the driven shaft. This feature has the advantage that at any rotation speed a varying pressure force is acting on the ground surface. This allows reducing the total weight of the roller unit while a similar smoothing efficiency is obtained by a roller unit with non-vibrating grass rollers.

In an embodiment, the vibrating movement has a frequency which is equal to the rotation speed of the driving shaft. When the rotation speed of the driving shaft is coupled to the driving speed of the roller unit, this allows obtaining a similar smoothness of the grass surface at any driving speed of the roller unit.

In an embodiment, the driven shaft passes through the vibrating grass roller. This feature enables to provide a very compact roller unit.

In a further embodiment, the vibrating grass roller comprises two or more grass roller sections, each grass roller section having an eccentric element structure and bearings to mechanically couple said grass roller section to the driven shaft. This feature reduces the extent to which, when making a turn, the surface of the roller slides instead of rolls over the grass surface. This can reduce the damage to the grass when the grass roller makes a turn. Another advantage of the grass roller with multiple roller sections is that unevenness perpendicular to the direction of travel of the roller unit is better followed. With a grass roller out of one piece with a length of for example 600mm, the lower located parts will never be touched. With a grass roller having 6 sections, the possibility that lower located parts are touched is increased as the stroke between two neighbouring roller sections can be used to touch the lower located parts.

In a further embodiment, the eccentric element structures of neighbouring grass roller sections are attached to the driven shaft with different angular orientation. This feature enables to increase the pressure force on the ground surface without reducing the length of the roller and increasing the weight of the roller unit. This feature improves the pressure efficiency of the roller unit.

In an embodiment, the roller unit comprises two or more vibrating grass rollers with a driven shaft passing through. This feature increases the area of the grass surface that is shaking. As a result compared with one vibrating roller, at the same driving speed of the roller unit, products such as sand and fertilisers will settle better in the top layer of the turf, as the time period the top layer is shaking is increased.

In an embodiment, the roller unit further comprises a pivotable assembly to couple mechanically two or more vibrating grass rollers to the frame. This feature allows the grass rollers to follow the curvature of the surface more accurately.

In an embodiment, the pivotable assembly is configured to allow the direction of the rotation axes of the two or more vibrating grass rollers to vary with respect to each other. With this feature, the rollers are better able to follow a curved grass surface, so that unevenness can be smoothed more efficiently. Furthermore, the surface is treated more intensively in the direction of travel, as several vibrating and rolling rollers interact with the same surface one after the other. This characteristic can be improved further by a pivotable assembly configured to allow the direction of the rotation axes of the two or more vibrating grass rollers to vary with respect to each other.

In an embodiment, the pivotable assembly comprises a main pivot part with a front section situated in front of a main pivoting point of the main pivot part and a rear section situated behind the main pivoting point. To each of the front section and rear section is attached a single grass roller or a sub pivot part with a sub pivoting point, a first grass roller is attached to the sub pivot part before the sub pivoting point and a second grass roller is attached the sub pivot part behind the sub pivoting point. This feature provides a roller unit with two or more vibrating rollers making a vibrating movement with respect to the driving shaft and frame with only one driving shaft.

In an embodiment, the pivotable assembly is mechanically coupled to the frame by means of a driven shaft, eccentric elements attached to the drive shaft and bearings around the eccentric elements.

In an embodiment, the roller unit comprises two pivotable assemblies, each pivotable assembly comprising a pair of two vibrating grass rollers. In this embodiment, the two pairs vibrate independently from each other which can improve the smoothing characteristics of the roller unit.

In an embodiment, the roller unit further comprises a coupling structure to couple the roller unit to a driving vehicle, the coupling structure comprises a shaft that is driven by the driving vehicle and which is mechanically coupled to the driven shaft to rotate the driven shaft. This feature reduces the costs and complexity of the roller unit as it does not need to comprise an integrated power source. 5 BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects, properties and advantages will be explained hereinafter based on the following description with reference to the drawings, wherein like reference numerals denote like or comparable parts, and in which: Fig. 1 shows schematically a perspective view of a first embodiment of a roller unit; Fig. 2 shows schematically a detailed view of the first embodiment in Fig. 1; Fig. 3A and 3B show schematically a side and front view of a grass roller of the first embodiment; Fig. 4 shows schematically a perspective view of a second embodiment of a roller unit; Fig. 5 shows schematically a sectional view of the second embodiment in Fig. 4; and, Fig. 6 shows schematically a side view of a roller assembly of a third embodiment of a roller unit.

DESCRIPTION OF EMBODIMENTS Fig. 1 and Fig. 2 show schematically a perspective view and detailed view of a first embodiment of a roller unit 100 for rolling lawns according to the present subject technology. The roller unit 100 comprises a frame 102, a driven shaft 104 attached to the frame with bearings 105, a rear roller 118, and one vibrating grass roller 106. The grass roller in the first embodiment comprises six grass roller sections. The number of grass roller sections forming one grass roller may be more or less than six, depending on the implementation of the roller unit. The driven shaft 104 is located transversely to the direction of travel of the roller unit. The driven shaft 104 is coupled with bearings 105 to frame 102. Side weights 116 are provided to compensate, for example, for the weight of a drive motor (not shown), such that both ends of the grass roller exert substantially the same pressure on the grass surface. The drive motor is coupled to transmission wheel 120. Belt 122 couples the transmission wheel 120 to a wheel 322, see Fig. 3A, attached to the driven shaft 104. The roller unit comprises a coupling structure 140 configured to couple the roller unit to a driving vehicle (not shown).

In the first embodiment, the driven shaft 104 passes through the vibrating grass roller. Eccentric elements 108 are fixed to the driven shaft 104 and bearings 110 around the eccentric elements mechanically couple the six grass roller sections to the frame 102 such that when the driven shaft is rotated, the at least one vibrating grass roller makes a vibrating movement relative to the driven shaft with a stroke in any direction in a plane perpendicular to the driven shaft. Each roller section 106 is coupled to the driven shaft 104 by two eccentric elements. A roller section consists of an outer cylinder, which is mounted with ring-shaped side plates and bearings 110 to the eccentric elements 108. Each roller section can therefore rotate freely around the eccentric elements and thus roll freely over the grass surface. The driven shaft with eccentric elements forms a kind of cam shaft, wherein the angle of the driven shaft and angular orientation of the eccentric elements of a roller section determine the position of the rotation axis of the roller section with respect to the position of the rotation axis of the driven shaft. When the driven shaft is rotating the position of the rotation axis of a roller section is rotating around the rotation axis of the driven shaft. The eccentric elements give the roller sections an imposed movement in all directions. The path of the imposed movement or stroke is defined by the eccentricity of the eccentric elements and is in the range of 1 -6 mm. In a fixed alternating sequence, the roll sections 106 will be pushed down to compress/smooth the grass surface while rolling over the grass surface. As the rotation axis of the driven shaft has a fixed position with respect to the frame, when rotation the driven shaft, the grass roller is moved up/down and forward/backward with a stroke which is defined by the eccentricity of the eccentric element(s) that couple the grass roller to the driven shaft. The vibrating movement has a predefined maximum stroke defined by the eccentricity and the vibrating movement has a frequency which is equal to the rotation speed of the driving shaft. Since the timing of all roller sections is fixed and accurately set, there will always be one roller section that is in full contact with the surface. The full mass of the roller unit then rests on this roller section,

resulting in a higher pressure and impact on the surface.

From Fig. 2 can be seen that two ring shaped elements 112 couple the grass roller section 106 to the bearings 110 around the eccentric elements 108. It should be noted that in the context of the present description a vibrating grass roller is a roller is actively moved with respect to the frame of the roller unit.

Thus a rear grass roller which rotation axis has a fixed position with respect to the frame is not a vibrating grass roller, despite the fact that the rear roller can make a vibrating movement when the frame also vibrates.

Fig. 3A and 3B show schematically a side and front view of a grass roller of the first embodiment.

Fig. 3A shows the driven shaft 104, wheel 322 where the drive belt goes around and a grass roller with six grass roller sections 106A, 106B, 106C, 106D, 106E and 106F.

As the eccentric elements of neighbouring sections have another angular orientation on the driven shaft, each neighbouring section has another position with respect to the driven shaft.

This is visible in Fig. 3A as different positions of the top and bottom of a roller section.

Fig. 3B is a left side view of Fig. 3A.

This Figure shows that the perimeters of sections 106A, 106B and 106C are in different positions.

An advantage of the first embodiment is that each time only a part of the surface of the grass roller along its length exerts a pressure force on the grass surface.

This pressure force is higher than a vibrating grass roller with only one section.

As a result, with the same weight of roller unit a roller unit with six roller sections exerts a pressure force per square centimeter on the grass surface which is higher than the pressure force per square centimeter of a roller unit with only one section.

Another advantage of the present technology is that when the roller unit rests on the ground by means of a rear roller and optionally also a front roller; the pushing of the vibrating roller is limited to a specified level below the level defined rear roller.

Now the depth of the specified level is defined by the eccentricity of the eccentric elements.

The velocity and acceleration at which the frame and roller are pushed apart by the eccentric elements determine the impact on the surface.

The mass of the roller on one side of the eccentric elements and the mass of the frame, drive motor and additional weights on the other side of the eccentric elements are important in this process.

In an alternative embodiment, the roller unit comprises further a front roller affixed to the frame.

With this embodiment, the working depth of the vibrating roller can be precisely adjusted.

It might also be possible to remove both the fixed front roller and rear roller.

Now the roller unit runs on the vibrating rollers or vibrating roller sections of a vibrating roller.

In an alternative embodiment, the roller unit comprises two grass rollers with a number of roller sections wherein the two grass rollers are placed in direction of travel after each other.

In this embodiment, when the roller unit travels over the grass surface, a vibrating force is applied two times to said grass surface, which makes the treatment more intensive.

Furthermore, the time period wherein a piece of grass surface is contiguous vibrating is longer.

As a result, sand and or other particles are better able to penetrate in the grass layer.

Fig. 4 shows schematically a perspective view of a second embodiment of a roller unit 400 according to the present subject technology.

A partially openwork frame is shown.

Fig. 5 shows schematically a sectional view of the second embodiment.

The roller unit 400 comprises a frame 402, a driven shaft 404 attached to the frame with bearings 405, a rear roller 418, and two vibrating grass roller 406A and 406B.

The driven shaft 404 is located transversely to the direction of travel of the roller unit.

The driven shaft 404 is coupled with bearings 405 to frame 402. Side weights 416 are provided to compensate, for example, for the weight of a drive motor (not shown), such that both ends of the grass rollers exert substantially the same pressure on the grass surface.

The drive motor is coupled to transmission wheel 420. A belt 422 couples the transmission wheel 420 to a wheel attached to the driven shaft 404. The driven shaft 404 is driven by the belt 422 with a higher rotation speed than the transmission wheel 420. The roller unit comprises a coupling structure 440 configured to couple the roller unit to a driving vehicle (not shown). Additional weights 426 can be added to increase the mass of the frame 402 and consequently the impact of the eccentric operation on the grass layer.

The rear roller 418 supports the rear of the frame 402 on the grass layer.

The roller unit 400 further comprises a pivotable assembly 430 configured to couple mechanically two vibrating grass rollers 406A, 406B to the frame 402. The pivotable assembly 430 comprises two pivot parts in the form of pivot plates.

The pivot parts are located at opposite ends of the vibrating grass rollers 406A and 406B.

Each pivot part is coupled in the middle to the driven shaft 404 by means of an eccentric element 408 and bearings 410. The pivotable assembly 430 is mounted eccentrically on the driven shaft 404. When the driven shaft is rotating the position of the pivot axis of the pivotable assembly is rotating around the rotation axis of the driven shaft. As the rotation axis of the driven shaft has a fixed position with respect to the frame, when rotation the driven shaft, the pivotable assembly 430 is moved up/down and forward/backward with a stroke which is defined by the eccentricity of the eccentric element(s) that couple the pivotable assembly 430 to the driven shaft 404. The vibrating movement has a predefined maximum stroke defined by the eccentricity and the vibrating movement has a frequency which is equal to the rotation speed of the driving shaft. The forces applied to the pivotable assembly by means of the rotating eccentric elements are distributed by the pivoting assembly between the two vibrating rollers. As a result, when at the same time one roller is on softer ground surface and the other on harder ground surface, the roller on the softer ground compresses the ground surface layer more than the roller on the harder ground.

In Fig. 5 is visible that both vibrating rollers 406A and 406B are connected to the pivoting assembly 430. The pivot part comprises a front section situated in front of a pivoting point of the pivot part and a rear section situated behind the pivoting point. To each of the front section and rear section is attached a single grass roller 406A, 406B. In the embodiment shown, the distance between the rotation axis of the two grass rollers and rotation axis of the pivot part 430 is similar. As a result forces exerted on the pivot part are distributed evenly of the two grass rollers and both grass rollers pushes on the grass layer with the same force. However, if the distance between the pivot axis of the pivot part and a first of the two rollers is two times the distance between the pivot axis of the pivot part and a second of the two rollers, the pushing force of the first is half the pushing force of the second on the ground surface. This may be advantageous such that in direction of travel of the roller unit, the first vibrating roller is used to smooth out the greatest unevenness of the grass surface and the second vibrating roller is used to further smooth out the remaining unevenness.

Fig. 6 shows schematically a side view of a roller assembly of a third embodiment of a roller unit. In this embodiment four grass rollers are attached to a pivotable assembly 630. The pivotable assembly 630 allows each roller to follow its own curved path over the grass, thus ensuring even roller compactions of the grass layer. An active vibrating movement is imposed on each of the multiple rollers, each following its own curvature. This is essential for a sloping green; otherwise the curvature will be “knocked down”. The pivotable assembly comprises a main pivot part 632C and two sub pivot parts 632A, 632B. The main pivot part 632C is pivotable attached to the driven shaft 604 by means of bearing

610. The sub pivot parts 632A, 632B are pivotable attached to the main pivot part 632C. The main pivot part 632C comprises a front section situated in front of a main pivoting point of the main pivot part and a rear section situated behind the main pivoting point. To each of the front section and rear section is attached a sub pivot part 632A, 632B with a sub pivoting point. A first grass roller 606A, 606C is attached to a sub pivot part before the sub pivoting point and a second grass roller (606B, 606D) is attached the sub pivot part behind the sub pivoting point.

If the pivot point of the main pivot part 632C is in the middle, the impact force on both sub pivot parts 632A, 632B will be the same. By positioning the pivot point away from the middle, the impact force can be adjusted for each sub pivot part. Similarly, if the pivot point of a sub pivot part 632A, 632B is in the middle, the impact force on both vibrating rollers will be the same. By positioning the pivot point away from the middle, the impact force can be adjusted for each grass roller.

The coupling of the rollers to the pivotable assembly can be flexible or elastic. If the coupling is flexible, the imposed movement from the eccentric elements is passed 1 to 1 on the rollers while the direction of the rotation axis of the individual rollers can vary with respect to each other to follow the curvature of the grass. If the coupling is elastic, the imposed movement from the eccentric elements can be flattened and distributed over a longer period of time.

The two eccentric elements 408 at both ends of the rollers can be placed in line. As a result, the rollers are moved simultaneously in the same direction. In order to increase the impact and reduce the imbalance, it is possible to place the two eccentric elements at 180° on the driven shaft 408. Now, opposite ends of the rollers are alternately pressed onto the grass layer.

The imbalance caused by the eccentric elements can also be reduced by placing balance weights on the driven shaft. One skilled in the art can play with balance weights by changing the angular position of the balance weights on the driven shaft, from being fully balanced to being completely out of balance with maximum impact on the rolling capacity of the rollers (vertical vibrating pressing and horizontal movement).

It is also possible to place, in one roller unit 4 rollers in two sections of 2 rolls, as shown in Fig. 4 and 5. By timing (angular position of an eccentric element) and driving both sections 180° to each other, the internal balance of the machine is improved and the impact on the turf is increased.

It is conceivable that in view of the fact that fewer pesticides may be used (against weeds and larvae), vibrating according to the present subject technology makes a possible contribution to the control of weeds and pests. It is very important that the vibration intensity exceeds a certain minimum threshold and that the soil is "shaken up".

While the invention has been described in terms of several embodiments, it is contemplated that alternatives, modifications, permutations and equivalents thereof will become apparent to those skilled in the art upon reading the specification and upon study of the drawings. The invention is not limited to the illustrated embodiments. Changes can be made without departing from the scope of the appended claims.

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Claims (15)

CONCLUSIONS: A rolling unit (100) for rolling lawns comprising: - a frame (102); - a driven shaft (104) attached to the frame with bearings (105); and, - at least one vibrating grass roll (106), characterized in that eccentric elements (108) attached to the driven shaft (104) and bearings (110) around the eccentric elements mechanically couple the at least one vibrating grass roll to the frame so that when the driven shaft is rotated, the at least one vibrating grass roller vibrates with respect to the driven shaft with one stroke in either direction in a plane perpendicular to the driven shaft. The roller unit of claim 1, wherein the vibrating motion has a predefined maximum stroke. The roller unit according to any one of claims 1 to 2, wherein the stroke is not related to the speed of the driven shaft. The roller unit according to any one of claims 1 to 3, wherein the vibrating movement has a frequency equal to the rotational speed of the drive shaft. The roller unit of any one of claims 1 to 4, wherein the driven shaft (104) passes through the at least one vibrating grass roller (106). The roll unit of claim 5, wherein the vibrating grass roll comprises two or more grass roll sections (106A...106F), each grass roll section having an eccentric element structure and bearings for mechanically coupling the grass roll section to the driven shaft. The roller unit of claim 6, wherein the eccentric element structures of adjacent grass roller sections of different angular orientation are mounted on the driven shaft. The roller unit of claim 7, wherein the eccentric element structures of all the grass roller sections of a grass roller are mounted on the driven shaft at different angular orientation. The roller unit according to any one of claims 5-8, wherein the roller unit comprises two or more vibrating grass rollers with a driven shaft, the driven shaft passing through the grass roller. The roller unit of any one of claims 1-9, wherein the roller unit further comprises a pivotable assembly (430, 630) for mechanically coupling two or more vibrating grass rollers to the frame. The roller unit of claim 10, wherein the pivoting assembly is configured such that the direction of the rotation axes of the two or more vibrating grass rollers can vary with respect to each other. The roller unit of any one of claims 10 to 11, wherein the pivotal assembly comprises a main pivot (632C) having a front portion in front of a main pivot of the main pivot and a rear portion behind the main pivot, each of the front and rear portions a single turf roll or sub-pivot portion (632A, 632B) having a sub-pivot point attached, wherein a first grass roll (606A, 606C) is attached to the sub-pivot sub-pivot portion and a second grass roll (606B, 606D) is attached to the sub pivot behind the sub pivot. The roller unit of any one of claims 10 to 12, wherein the pivotal assembly (430, 630) is mechanically coupled to the frame by means of a driven shaft (404, 604), eccentric members (408, 608) mounted on the driven shaft and bearings (410, 610) around the eccentric elements. The roller unit of any one of claims 10 to 13, wherein the roller unit comprises two pivotable assemblies, each pivotal assembly including two vibrating grass rollers. The roller unit of any one of claims 1 to 14, wherein the roller unit further comprises a coupling structure (120, 420) for coupling the roller unit to a driving vehicle, the coupling structure comprising a shaft driven by the driving vehicle and mechanically connected to the driven shaft is coupled to rotate the driven shaft. -O0-0-0-0-0-0-