Mobile joint cutter with reduced hand-arm accelerations

Abstract

Joint cutting device, comprising: a motor (8), a chassis (1) with a chassis frame (2) and wheels (3) supporting the chassis frame (2), a support device (6, 7) for supporting the motor (8) on the chassis frame (2), and a tool holder for receiving a cutting tool, wherein: the tool holder is mounted on the chassis frame (2) and can be rotated by the motor (8), the support device comprises a support frame (6) and several vibration decoupling elements (7), the motor (8) is detachably mounted on the support frame (6), the vibration decoupling elements (7) are arranged between the support frame (6) and the chassis frame (2), the motor (8) is movably mounted relative to the tool holder via the vibration decoupling elements (7), the vibration decoupling elements (7) are oriented such that they have their lowest stiffness in the horizontal direction, the The support frame (6) has a depression (10),and wherein the support frame (6) has raised support areas (11) laterally to the lowering (10), on each of which a vibration decoupling element (7) is arranged.

Description

[0001] The invention relates to a joint cutting device, in particular a mobile joint cutter.

[0002] Mobile joint cutters for cutting materials such as asphalt or concrete are well-known. For example, they are used to create an expansion joint in an asphalt surface, allowing the relevant section of the asphalt to be removed and a trench to be excavated.

[0003] Such a joint cutter has a chassis with a frame that can be moved across the ground by means of wheels. The chassis carries a drive motor that rotates a tool holder. A suitable tool, for example, a cutting disc, can be inserted into the tool holder, which then rotates with the tool holder, thereby cutting the underlying material as desired. In larger joint cutters, the motor can also be used to propel the entire device via the wheels. Alternatively, and especially in smaller joint cutters, the chassis is moved manually by an operator.

[0004] The operator guides the joint cutter using a corresponding guide handle or bracket, allowing them to regularly monitor its direction. For this purpose, the operator must hold the handle continuously, which means that vibrations generated by the joint cutter are transmitted to the operator, particularly to their hands and arms. These vibrations and accelerations can therefore be stressful for the operator over time.

[0005] In simple joint cutters, the motor is mounted directly on the chassis frame, so that the vibrations emanating from the motor are transmitted directly to the operator via the chassis frame and the handle.

[0006] From WO 2007 / 082066 A2, a joint cutting device is known in which the tool holder and a cutting shaft supporting the tool holder are rigidly connected to the motor. The cutting shaft and the motor are mounted together with springs relative to the chassis frame. This allows for vibration decoupling of the chassis frame and thus also the handle. However, the rigid connection between the motor and the cutting shaft means that the vibrations of the motor are transmitted to the cutting tool (cutting disc), so that the cut becomes unnecessarily wide due to the oscillating movement of the cutting disc, and the cutting disc wears out faster due to the increased load.

[0007] GB 2418000 A describes a joint cutting device in which the motor is mounted on a complex support structure with laterally inclined fixings. While this also achieves vibration decoupling between the motor and the chassis frame, the design requires considerable effort and therefore incurs significant costs.

[0008] The invention is based on the objective of providing a joint cutting device in which the operator is reliably decoupled from the vibrations generated in or on the motor. Furthermore, the effects of vibration on the cutting tool are to be minimized by not connecting it directly to the motor via a rigid connection.

[0009] The problem is solved according to the invention by a joint cutting device having the features of claim 1. Advantageous embodiments are specified in the dependent claims.

[0010] A joint cutting device comprises a motor, a chassis with a chassis frame and wheels supporting the chassis frame, a support structure for mounting the motor on the chassis frame, and a tool holder for receiving a cutting tool. The tool holder is mounted on the chassis frame and is driven by the motor. The support structure includes a support frame and several vibration damping elements, with the motor detachably mounted on the support frame and the vibration damping elements arranged between the support frame and the chassis frame. The motor is movably mounted relative to the tool holder via the vibration damping elements. The vibration damping elements can be oriented such that they exhibit their lowest stiffness in the horizontal direction.

[0011] Because the motor is movable relative to the tool holder via the vibration decoupling elements, effective vibration decoupling between the motor and the tool holder can be achieved. This prevents, or significantly reduces, the vibrations generated in the motor from being transmitted to the tool holder and thus to the cutting tool.

[0012] The same applies to the vibration decoupling of the chassis frame. Here, too, the vibration decoupling elements arranged between the support frame and the chassis frame act in such a way that the chassis frame is only subjected to minor vibrations and accelerations, so that only these reduced accelerations can be transmitted to the guide handle and thus to the operator. The operator is therefore exposed to lower accelerations.

[0013] The vibration isolation elements exhibit their lowest stiffness in the horizontal direction, i.e., in a horizontal plane. This means, for example, that the vibration isolation elements are essentially installed vertically between the chassis frame and the support frame. In the vertical direction, the vibration isolation elements can effectively absorb the load resulting primarily from the engine weight and the tension of the drive belt, while vibrations in the horizontal direction, due to their lower stiffness, can be absorbed by the flexibility of the vibration isolation elements.

[0014] The support frame can have a recess, in particular a recess extending longitudinally or transversely to the chassis frame (direction of travel), wherein the support frame can have raised support areas laterally to the recess, each of which houses a vibration isolation element. The recess between the raised support areas allows the motor to be installed relatively low, resulting in a low overall height for the joint cutter. The support frame essentially hugs the underside of the motor and is raised laterally to the recess, and thus laterally to the area where the motor is supported, by the support areas. The raised support areas allow for the installation of sufficiently large vibration isolation elements in the space below them. The support frame with the motor is therefore supported on the chassis frame via these support areas.

[0015] In particular, it may be useful to provide four support areas, namely – in relation to the longitudinal direction – two to the left and two to the right of the motor or the lowering mechanism.

[0016] A drive belt can run between the motor and the tool holder, for rotating the tool holder. A transverse recess can be formed in the support frame on a transverse side facing the drive belt, between two belt-side support areas, with the drive belt running through this transverse recess.

[0017] To implement this belt drive system, a suitable drive pulley can be mounted on the motor shaft, for example, to guide and drive the drive belt. The drive belt is guided vertically or diagonally downwards from the motor located above to the tool holder, which is, for example, mounted on a cutting shaft in the lower part of the chassis frame. A pulley is also provided there to transmit the drive torque of the drive belt.

[0018] On the transverse side of the support frame, where the drive belt is guided downwards, a transverse recess is formed in the frame between the two belt-side support areas (each with vibration damping elements). This transverse recess allows the drive belt to be guided downwards to the cutting disc or tool holder. The transverse recess thus forms a passage through which the drive belt can be guided downwards past the support frame.

[0019] In one variant, the two belt-side support areas and the drive belt can lie on a common (imaginary) line. The pretension of the drive belt exerts a considerable tensile force, which pulls the drive motor downwards on the drive pulley. This tensile force must be supported, which results in a force flow primarily through the two belt-side support areas and the vibration decoupling elements located beneath them. If the two belt-side support areas with their vibration decoupling elements, on the one hand, and the drive belt, on the other, lie on a common line, a tilting moment on the support plate is prevented. This eliminates the need for additional support elements, such as those described in GB 2418000 A.

[0020] On a transverse side of the support frame facing away from the drive belt, a further transverse recess can be formed, extending longitudinally. This additional transverse recess can, for example, be essentially symmetrical to the first transverse recess on the belt side. This additional transverse recess allows the motor to be moved longitudinally on the support frame to adjust its position, for example, to different drive belt lengths. Without this additional transverse recess, there would be a risk of the motor, or parts of the motor, colliding with the support frame, necessitating a wider support frame overall. Furthermore, this additional transverse recess serves to reduce the overall weight of the device.

[0021] In one design, the support frame can be configured as a support plate, with the motor mounted on its upper surface. This support plate design is particularly simple for constructing the support frame. In particular, no additional components are required. The support plate can be designed to incorporate the features mentioned above, namely the longitudinal depression, the raised support areas, and the transverse recesses on the transverse sides.

[0022] The profiling, especially the desired lowering in the central area, stabilizes the support plate in such a way that no additional stiffening structural elements are necessary, resulting in a significant weight saving.

[0023] The mounting plate may have elongated holes through which fasteners can be inserted to attach the motor to the plate. This allows the motor to be easily moved back and forth on the mounting plate after loosening the fasteners (e.g., screws) to, for example, achieve the desired belt tension in the drive belt. The fasteners do not need to be completely unscrewed for this purpose; they can also be moved back and forth within the elongated holes.

[0024] The vibration decoupling elements can be selected from the following group: all vibration decoupling elements have the same spring stiffness, at least two vibration decoupling elements have different spring stiffnesses, the vibration decoupling elements provided on the belt-side support areas have a higher spring stiffness than the other vibration decoupling elements, the vibration decoupling elements are identical in construction, at least two vibration decoupling elements have a different height.

[0025] The varying heights of the components allow for the different deflections resulting from varying loads and any subsequent settling of the vibration damping elements. Alternatively, height-compensating elements can be used instead of different heights.

[0026] The vibration decoupling elements can each have a rubber buffer. Rubber buffers are particularly suitable for implementing the vibration decoupling elements in a simple, yet effective and durable manner.

[0027] The rubber buffers can be designed accordingly. For example, all rubber buffers can have the same spring stiffness, or at least two rubber buffers can have different spring stiffnesses. This makes it possible, for instance, to equip the rubber buffers on the belt-side support areas with a higher spring stiffness than the other, opposing rubber buffers, in order to compensate for the tensile force of the drive belt. It is also possible to design the rubber buffers with different heights.

[0028] The rubber buffers can have a central axis that is vertically oriented when installed. These typically cylindrical rubber buffers are thus installed with their central axis perpendicular to the chassis frame and the support frame. The central axis also serves as a mounting point for fasteners. For example, screws can be screwed into corresponding metal threads located inside the rubber buffers. It is also possible to pass fasteners such as screws through the rubber buffers. Crucially, the two sides of the rubber buffers are not rigidly connected, but rather solely by the rubber itself, in order to achieve the desired vibration-damping effect.

[0029] The rubber buffers can be arranged on the chassis frame in a common plane or in two parallel planes. For example, the rubber buffers closer to the front wheels can be arranged in a different plane than those closer to the rear wheels. Furthermore, the central axes of the rubber buffers can be perpendicular to this plane. In this case, no special requirements apply to the support plate or frame above.

[0030] The spacing between the rubber buffers can be chosen such that the vibration load on the chassis frame is minimized during operation of the joint cutting device. Thus, the spacing of the rubber buffers is not determined by the dimensions of the support plate or the motor, but rather by the criterion of minimizing vibrations on the chassis frame. For this purpose, a person skilled in the art will generate the joint cutting device in a CAD system and conduct vibration tests using standard simulation systems. By changing the relative positions of the rubber buffers, it is readily possible to minimize the vibrations transmitted to the chassis frame.

[0031] If vibrations in the chassis frame are successfully minimized, additional supporting or stabilizing elements on the chassis frame can be omitted. In particular, no further stiffening ribs or support plates are necessary, which are usually installed in joint cutters to increase the stability of the chassis frame. This saves material, weight, and costs.

[0032] In the prior art, it is common practice to distribute any vibration decoupling elements, if required, solely based on the engine's dimensions, ensuring easy access and reliable engine support. However, determining the positions and spacing of the rubber buffers based on the criterion of minimizing vibration load on the chassis frame was previously unknown.

[0033] These and other features and advantages will be explained in more detail below using an example and the accompanying figures. They illustrate:

[0034] Fig. 1 a joint cutting device in perspective view (without motor and without cutting tool);

[0035] Fig. 2 the joint cutting device of Fig. 1 from a different perspective view, additionally without drive belt;

[0036] Fig. 3 the joint cutting device of Fig. 2 in side view;

[0037] Fig. 4 the joint cutting device with motor in side view; and

[0038] Fig. 5 a front view of the joint cutting device of Fig. 4.

[0039] The Fig. 1 to Fig. Figure 5 shows the same joint cutting device overall, although some components have been omitted or included for better illustration and explanation.

[0040] Fig. Figure 1 shows the joint cutting device with a chassis 1 , which includes a chassis frame 2 as well as wheels 3 , namely rear wheels 3a and front wheels 3b , exhibits. Fig. 1 are simply the two rear wheels 3a visible. In addition, two more wheels (front wheels) are visible below and concealed by the chassis frame. 3b ) arranged, as also from the Fig. 3 to Fig. 5 is visible.

[0041] Above the chassis frame 2 A frame rises 4 , on which a guide handle 5 It is mounted in a height-adjustable manner, over which an operator can guide, push, or move the joint cutting device.

[0042] Depending on the design, the chassis frame can 2 be covered by a covering so that the top and side surfaces are smooth, as for example in Fig. 1 shown.

[0043] On the top of the chassis frame 2 is a support plate 6 arranged, which serve as vibration decoupling elements via a total of four rubber buffers 7 on the chassis frame 2 are supported. The support plate 6 It serves to support an engine. 8 , who in the Fig. 4 and Fig. 5 is shown. The engine 8 is on the support plate 6 fastened and held, for example, by screws (not shown) that pass through elongated holes 9 in the support plate 6 are inserted through. The motor 8 It has a fuel tank on its upper side. 8a .

[0044] The support plate 6 It has a longitudinal direction X extending in the direction of travel. In the middle there is a depression extending in the longitudinal direction X. 10 trained, which serves to determine the positional level of the engine8 to reduce the height of the joint cutting device as much as possible. In this way, the motor sits relatively close to the top of the chassis frame. 2 The reduction 10 in the support plate 6 is in Fig. 5 marked with A.

[0045] To the left and right of the dip 10 (viewed in the direction of travel or longitudinal direction X) there are two rubber buffers each. 7 arranged. The support plate 6 supported by cantilevers 11 on the rubber buffers 7 off. The cantilevers 11 serve as support areas for the support plate 6 .

[0046] To provide sufficient installation space for the rubber buffers arranged underneath 7 The cantilevers are to be reached 11 pulled slightly upwards, as can be seen in the figures.

[0047] Fig. Figure 1 shows a drive belt 12, which uses a drive pulley 13 is guided and deflected. The drive pulley 13 appears in Fig. 1 to float. However, this is due to the illustration, because the motor 8 The motor shaft was omitted for illustrative purposes. The drive pulley is actually located... 13 on the motor shaft and is driven by the motor 8 driven by rotation.

[0048] The drive power is transmitted via the drive pulley 13 and the drive belt 12 The path leads downwards to a cutting shaft (not shown) and a tool holder arranged thereon in a known manner. A cutting tool, in particular a cutting disc, can be inserted into the tool holder, which is also generally known and therefore not shown in detail in the figures.

[0049] The drive belt 12 and the drive pulley 13are through a belt cover 14 covered.

[0050] Due to the longitudinal displacement of the engine 8 on the support plate 6 Is it possible to adjust the tension of the drive belt? 12 easy to adjust.

[0051] The support plate 6 points to the drive belt 12 a transverse recess on the facing transverse side 15 on, which is essentially a cutout in the support plate 6 forms. The transverse recess 15 is dimensioned in such a way that the drive belt 12 and the rubber buffers arranged on the drive belt side 7 lie on an imaginary common line. This allows the components in the drive belt to lie on a common line. 12 tensile forces acting through the two rubber buffers 7 They are effectively absorbed and supported. In particular, tilting or bending moments are avoided.

[0052] The rubber buffers 7They are therefore vertically oriented, meaning that their central axis extends vertically upwards. This implies that the rubber buffers 7 They exhibit their lowest stiffness in the horizontal direction. In all other directions, the stiffness is greater, so that the stiffness is particularly affected by the motor. 8 or the tension in the drive belt 12 The resulting loads can be absorbed well. The lower stiffness in the horizontal direction, however, allows the chassis frame to be designed with a more flexible design. 2 to decouple from engine vibrations.

[0053] On the drive belt 12 opposite side of the support plate 6 can a further transverse recess 16 This may be provided. It can be useful to allow the motor to be moved and installed in different positions along the longitudinal axis X. Motor components 8 otherwise, they would be used with the support plate 6collide. Due to the further transverse recess 16 These components can also be moved in the longitudinal direction X.

[0054] The spacing of the rubber buffers 7 The relationship between them is optimized in such a way that the vibrations or accelerations caused by the motor are minimized. 8 into the support plate 6 to be initiated, only slightly affecting the chassis frame 2 can be transferred. The chassis frame 2 It can therefore be made less rigid. In particular, it is possible to omit additional stiffening components such as ribs or tabs. For optimizing the spacing of the rubber buffers 7 It is advisable to generate the joint cutting device in a CAD system and to simulate corresponding vibrations using standard simulation programs.

[0055] As already stated, the joint cutting device is not fully shown in some figures in order to better show details.

[0056] Fig. Figure 4 shows a right-hand view of the joint cutting device, with a tool or cutting disc cover. 17 .

[0057] The reduction of the amount of material in the chassis 1 The introduced vibrations and accelerations increase the service life of the individual components and relieve the operator who holds the joint cutter by the guide handle. 5 leads. QUOTES INCLUDED IN THE DESCRIPTION

[0058] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0059] WO 2007 / 082066 A2

[0006] GB 2418000 A [0007, 0019]

Claims

[1] Joint cutting device, with – an engine ( 8 ), – a chassis ( 1 ), with a chassis frame ( 2 ) and wheels ( 3 ), which the chassis frame ( 2 ) carry, – a support device ( 6 , 7 ) to carry the engine ( 8 ) on the chassis frame ( 2 ), and with – a tool holder for receiving a cutting tool, wherein – the tool mount on the chassis frame ( 2 ) is stored and driven by the motor ( 8 ) can be driven by rotation, – the support device a support frame ( 6 ) and several vibration decoupling elements ( 7 ) shows, – the engine ( 8 ) on the support frame ( 6 ) is detachably attached, – the vibration decoupling elements ( 7 ) between the support frame ( 6 ) and the chassis frame (2 ) are arranged, – the engine ( 8 ) via the vibration decoupling elements ( 7 ) is movably mounted relative to the tool holder, and wherein – the vibration decoupling elements ( 7 ) are aligned in such a way that they exhibit their lowest stiffness in the horizontal direction. [2] Joint cutting device according to claim 1, wherein the support frame ( 6 ) a lowering, in particular a lowering in the longitudinal direction (X) or in the transverse direction of the chassis frame ( 2 ) extending subsidence ( 10 ) has and wherein the support frame ( 6 ) laterally from the lowering ( 10 ) increased support areas ( 11 ) has a vibration decoupling element on each of which ( 7 ) is arranged. [3] Joint cutting device according to claim 1 or 2, wherein – between the engine ( 8 ) and the tool holder a drive belt (12 ) runs, to drive the tool holder by the motor ( 8 ), – on one of the drive belts ( 12 ) facing transverse side of the support frame ( 6 ) between two belt-side support areas ( 11 ) a transverse recess ( 15 ) in the support frame ( 6 ) is trained, and whereby – the drive belt ( 12 ) through the area of ​​the transverse recess ( 15 ) proceeds. [4] Joint cutting device according to one of the preceding claims 1 to 3, wherein the two belt-side support areas ( 11 ) and the drive belt ( 12 ) lie on a common line. [5] Joint cutting device according to one of the preceding claims 1 to 4, wherein on one of the drive belts ( 12 ) opposite side of the support frame ( 6 ) another transverse notch ( 16 ) on the support frame ( 6) is formed, which extends in the longitudinal direction (X). [6] Joint cutting device according to any one of the preceding claims 1 to 5, wherein the support frame serves as a support plate ( 6 ) is trained and the engine ( 8 ) on the top side of the support plate ( 6 ) can be attached. [7] Joint cutting device according to any one of the preceding claims 1 to 6, wherein in the support plate ( 6 ) Longitudinal holes ( 9 ) are designed, through which fastening means can be passed to secure the motor ( 8 ) on the support plate ( 6 ) to attach. [8] Joint cutting device according to any one of the preceding claims 1 to 7, wherein the vibration decoupling elements are selected from the group: – all vibration decoupling elements have the same spring stiffness, – at least two vibration decoupling elements have different spring stiffnesses, – those on the belt-side support areas ( 11 The vibration decoupling elements provided have a higher spring stiffness than the other vibration decoupling elements. – the vibration decoupling elements are identical in design, – at least two vibration decoupling elements have different heights. [9] Joint cutting device according to any one of the preceding claims 1 to 8, wherein the vibration decoupling elements each have a rubber buffer ( 7 exhibit. [10] Joint cutting device according to any one of the preceding claims 1 to 9, wherein the rubber buffers ( 7 ) have a central axis that is vertically oriented. [11] Joint cutting device according to any one of the preceding claims 1 to 10, wherein the rubber buffers ( 7 ) are arranged in a common plane and / or the rubber buffers ( 7) are arranged in two parallel planes and / or the central axes of the rubber buffers ( 7 ) perpendicular to the plane. [12] Joint cutting device according to any one of the preceding claims 1 to 11, wherein the distance between the rubber buffers ( 7 ) is selected in such a way that the vibration load on the chassis frame ( 2 ) is minimized during the operation of the joint cutting device.

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