MATERIAL SEPARATION DEVICE

Description

[0001] The invention relates to a material cutting device, such as a floor cutter, a power cutter, a cutting saw, or a chainsaw. The material cutting device can be movable on a frame or handheld.

[0002] A typical mobile joint cutter with belt drive serving as such a material separation device is known from DE 10 2014 010 354 A1.

[0003] The floor saw has a rotating tool holder that supports the cutting disc, which serves as the tool. The tool holder is usually driven by a belt drive, which in turn is powered by an internal combustion engine or electric motor. The motor is located above and—as seen in the direction of travel—behind the cutting axis.

[0004] The cutting depth relevant for practical use, both downwards (when the floor saw is in its intended working position) and forwards, is limited by the cutting disc radius and, ideally, only by the radius of the tool holder (clamping fixture) for the cutting disc. Accordingly, it is advantageous if the diameter of the output-side pulley is not larger than the diameter of the tool holder supporting the cutting disc.

[0005] For space reasons, this design typically requires the drive motor to be offset behind the cutting shaft so that it doesn't protrude forward. The forward direction of travel is the primary cutting direction in which the floor saw is moved. Accordingly, only a portion of the motor's mass acts as a cutting load, thus counteracting the cutting disc's upward movement. Due to the cutting disc's direction of rotation, there is a tendency for the cutting disc to lift itself out of the material being cut.

[0006] The belt drive or other torque transmission requires structural effort, which is associated with additional costs and a reduction in overall efficiency.

[0007] A direct drive of the tool holder without an intermediate torque transmission is possible. For this purpose, an electric motor can be mounted directly on the cutting shaft. However, conventional electric motors are too large to accommodate the high power and torque requirements, necessitating a correspondingly large outer diameter of the stator or motor housing. This outer diameter is usually larger than the diameter of typical clamping fixtures for cutting discs. This reduces the possible cutting depth.

[0008] From CN 107 553 602 A, a sawing device is known in which the rotor of an electric motor driving the device and the saw blade form a structural unit. The rotor is integrated into the saw blade. The stator of the electric motor encloses the rotor or the saw blade over an angle of less than 180 degrees. CN 107 553 602 A shows a material cutting device according to the preamble of the appended claim 1.

[0009] A similar arrangement is known from SU 1 726 273 A1.

[0010] The invention is based on the object of providing a material separation device in which the disadvantages of the prior art are avoided.

[0011] According to the invention, the object is achieved by a material separation device having the features of claim 1. Advantageous embodiments are specified in the dependent claims.

[0012] A material cutting device comprises a rotatably mounted tool holder configured to support a cutting tool. Furthermore, the material cutting device comprises a drive for rotating the tool holder. The drive comprises an electric motor with a rotor and a stator. The rotational axis of the rotor of the electric motor and the rotational axis of the tool holder are arranged coaxially with each other, and the stator surrounds the rotor over an angle of less than 360°.

[0013] The material cutting device can be, for example, a joint cutter, a cut-off grinder, a cut-off saw, or a circular saw. Accordingly, the cutting tool can be, for example, a cutting disc or a saw disc.

[0014] The drive is provided by an electric motor mounted on the cutting shaft so that the rotor's rotational axis is coaxial with the rotational axis of the tool holder. This eliminates the need for a torque transmission or torque converter, such as a belt drive. Instead, the electric motor directly drives the tool holder and thus the cutting tool.

[0015] However, the electric motor used is not a conventional motor, but rather an electric motor in which the stator extends over an angle of less than 360°. Thus, the stator does not completely enclose the rotor, e.g., in a ring or tube-like configuration, as in a conventional electric motor. Instead, the electric motor can be a segment motor, in which the stator is located in only one or more segments.

[0016] In this way, it is possible to design the electric motor in such a way that the stator does not extend beyond the rotor diameter on at least one side (e.g. downwards).

[0017] The electric motor can be a reluctance machine, particularly a synchronous reluctance machine. A synchronous reluctance machine with a segmented stator has proven particularly suitable, in which the stator extends only over a specific angular range (stator block).

[0018] In this way, the electric motor can be designed in such a way that the stator and the rotor, including their housing (electric motor housing), do not extend downwards and forwards (in the direction of travel) in the cutting direction beyond the diameter of the tool holder (e.g. a clamping holder).

[0019] Since no torque transmission or torque conversion is required, considerable construction effort and thus costs can be saved. The elimination of torque transmission allows the material cutting device to achieve a higher overall efficiency, while the cutting depth is not reduced beyond the limitation of the tool holder. Furthermore, the electric motor is mounted on a common axis with the tool holder, so that the weight force generated by the entire mass of the electric motor can be used as a counterforce against the forces acting during cutting. In particular, the electric motor presses the cutting tool downward into the material to be cut.

[0020] The stator encloses the rotor over an angle of less than 360°. This means that the motor stator can no longer be designed as a closed rotating part or as a closed ring, but can only extend over a specific angular range. Accordingly, the stator can be designed as a stator segment or stator block and extend over an angle of, for example, 270° or less, 180° or less, 120° or less, or 90° or less. In practice, an enclosure of approximately 180° has proven to be suitable.

[0021] Accordingly, it is also possible to distribute several stator segments or stator blocks around the circumference of the rotor, which can increase the performance of the motor and in particular the torque of the motor.

[0022] The angular range over which the stator segment, or possibly the multiple stator segments, extend is selected such that the stator does not impair the usable cutting depth. In particular, the stator does not extend beyond the diameter of the tool holder in the direction of the cutting location (separation location).

[0023] The stator may extend over an angle dimensioned such that the stator is located exclusively on one side of an interface, wherein the interface is defined as a virtual tangential surface on an outer side of the tool holder.

[0024] The interface can therefore be defined as a virtual (imaginary) tangential surface that lies tangentially against the outside of the tool holder (especially its underside). The stator should not extend beyond this interface to avoid reducing the usable cutting depth. Rather, the cutting depth (separation depth) in this area should be limited solely by the diameter of the tool holder. Components of the electric motor, especially the stator, should not extend beyond the tool holder in the direction of the cutting location (separation location).

[0025] In one embodiment, the interface can be a virtual horizontal plane defined as a tangential surface on the underside of the tool holder when the material cutting device is in a proper position. In this case, the material cutting device can be, for example, a joint cutter, in which the cutting disc serving as the tool extends substantially downwards to cut the material there.

[0026] In this case, the interface limits the contour of the stator downwards. Accordingly, the stator must not extend beyond the interface or protrude downwards. Rather, the stator should be positioned exclusively above the interface.

[0027] The lowest level to which the stator may extend downwards is thus defined in particular by the cylindrical outer side of the tool holder.

[0028] The requirement for the stator accordingly also applies, where appropriate, to a housing that serves as an electric motor housing and at least partially encloses the stator.

[0029] The tool holder can be designed to be substantially rotationally symmetrical, with the tool holder having a maximum radius (clamping radius), and with the stator not extending beyond the maximum radius of the tool holder in a downward and forward direction when the material cutting device is in its intended working position. The intended working position depends in particular on the design of the material cutting device. If the material cutting device is designed as a joint cutter, the main direction of travel is forward. The cutting action is generated downwards.

[0030] The material separation device can be a joint cutting device, with a chassis and with at least one chassis for moving the chassis, wherein the electric motor and the tool holder are arranged in a front region of the chassis, seen in the main direction of travel, and wherein an electrical energy storage device is provided for supplying the electric motor with electrical energy.

[0031] The chassis can, for example, have an axle with two rollers. This makes it possible to tilt the chassis around the chassis. Typically, however, the chassis will have two axles, each with two rollers, so that the entire joint cutting device can be moved on four rollers. In addition, the chassis can also be equipped with a guide handle, which an operator can use to move the material cutting device.

[0032] The center of gravity of the electrical energy storage device can be positioned above the rotational axis of the tool holder. This advantageously results in the weight of the electrical energy storage device, e.g., a battery, pressing the cutting tool downward into the material to be cut. This counteracts the frequently observed upward movement that occurs during cutting due to the rotation of the cutting tool.

[0033] The battery's center of gravity should be positioned closer to a location vertically above the motor's rotation axis (and thus also the tool's rotation axis) than to a location above the rotation axis of the chassis' rollers. In particular, the center of gravity should be positioned as far forward as possible, in the direction of travel, to achieve the desired hold-down of the cutting tool.

[0034] In one variant, the center of gravity of the electrical energy storage device can be arranged substantially vertically above the axis of rotation, so that the weight of the energy storage device acts in the best possible way to press down the cutting disc.

[0035] A battery holder can be provided to accommodate the electrical energy storage device, which can be replaceable. The battery holder accommodates the energy storage device in a replaceable manner, allowing a used battery to be replaced very easily and quickly with a new one.

[0036] The chassis can, in its intended working position, have a lower section at the level of the electric motor and the tool holder, whereby the chassis can also have an upper section which is arranged above the lower section and is spaced from the lower section by at least 400 mm. The lower and upper sections offer options for suitably positioning the components required for the electrical power supply on the joint cutting device. For example, the battery can be arranged in the lower section and a converter device in the upper section. It is also advisable for the guide bar for an operator to guide the machine to be attached to the upper section.

[0037] Accordingly, a converter device can be provided in the upper or lower region for converting an electrical direct current from the electrical energy storage device into a current suitable for operating the electric motor.

[0038] These and other advantages and features of the invention are explained in more detail below using examples with the aid of the accompanying figures. They show: Fig. 1 in side view a material separating device according to the invention as a joint cutter; Fig. 2 an enlarged detail of the joint cutter from Fig. 1 electric motor used; Fig. 3 a bottom view of the joint cutter from Fig. 1 ; Fig. 4 a rear view of the floor cutter from Fig. 1 ; Fig. 5 a variant of the joint cutter from Fig. 1 ; Fig. 6 a bottom view of the joint cutter from Fig. 5 ; Fig. 7 a rear view of the floor cutter from Fig. 5 ; and Fig. 8 in schematic representation a circular saw as a further embodiment of a material cutting device according to the invention.

[0039] The Fig. 1 to 4 show a first variant of a joint cutter as a material separation device according to the invention.

[0040] The joint cutter comprises a chassis 1 with a chassis frame 2 and a running gear 3. On the running gear 3, two front wheels 4 and two rear wheels 5 are provided, each of which is arranged on an axle 6 ( Fig. 3 ).

[0041] In the upper area of ​​the chassis 1 or the chassis frame 2, a guide handle 7 is mounted which can be pivoted in height and by means of which an operator can guide, push or move the joint cutter.

[0042] Depending on the design, the chassis 3 can be covered by a cover so that the top and side surfaces are smooth, as in Fig. 1 shown.

[0043] In the upper area of ​​the chassis 1, a height adjustment 8 is also provided, which in the example shown is designed as a crank and with which an operator can adjust the lowering of a cutting device 9 relative to the rest of the chassis 1 in a manner known per se.

[0044] The cutting device 9 has a cutting disc 10 serving as a cutting tool, which is rotatably mounted in a clamping fixture 11 serving as a tool holder. The cutting disc 10 can be replaced as needed, for which purpose the clamping fixture 11 can be easily opened and closed.

[0045] Coaxial with the clamping fixture 11, an electric motor 12 serving as a drive is provided, comprising a rotor 13 and a stator 14. A rotor shaft 15 of the rotor 13 extends to the clamping fixture 11, so that the clamping fixture 11 can be driven in rotation directly by the rotor 13.

[0046] In conventional electric drives, the stator 14 would completely enclose the rotor 13 in a circular ring. In the material separation device according to the invention, however, the electric motor 12 is designed as a segment motor, with the stator 14 extending only over a limited angular range of less than 360°. In the example shown by Fig. 1 and - as a detail enlargement - Fig. 2 It can be seen that the stator only extends over an angular range (segment) of approximately 180° around the rotor 13.

[0047] Rotor 13 and stator 14 are also enclosed by a housing 16. It is clearly visible that the housing 16 can be very compact due to the small size of the stator 14, which extends over only one segment.

[0048] Especially in Fig. 2It can be seen that the stator 14 does not extend any further downwards than the rotor 13. In a conventional electric motor with a ring-shaped stator, the stator would also take up considerable space below the rotor 13. This is the case with the Fig. 1 and 2 However, this is not the case with the solution shown. Especially at the bottom, the installation space is limited to the diameter of the rotor 13 (and the surrounding housing 16). No further installation space is required at the bottom.

[0049] If the rotor diameter (including the housing 16) is smaller, and certainly not larger, than the diameter of the tool holder or clamping fixture 11, the diameter of the clamping fixture 11 alone is the limiting factor for the cutting depth. The cutting disc 10 can thus penetrate very deeply into the material to be cut. The penetration depth is limited only by the diameter of the clamping fixture 11. The design of the electric motor 12 does not require any limitation of the penetration depth or cutting depth.

[0050] This connection is also in Fig. 4. The rear view shows the clamping fixture 11 and the electric motor 12 side by side. In particular, it can be seen that the electric motor 12, and thus the stator 14 including the housing 16, do not extend downward beyond a virtual horizontal plane 17, which is defined tangentially on the underside of the tool holder 11 and extends perpendicular to the plane of the drawing. Thus, the electric motor 12 does not reduce the possible downward penetration depth of the cutting disk 10.

[0051] A battery 18 is arranged in the lower area of ​​the chassis 1 as an electrical energy storage device. The battery 18 can, in particular, be mounted in a replaceable manner in a corresponding battery holder, so that it can be quickly replaced with a fresh battery 18 if necessary.

[0052] A converter 19 is arranged in the upper area of ​​the chassis 1. It serves to convert the direct current drawn from the battery 18 into a suitable current for the electric motor 12. This is particularly necessary when the electric motor 12 is a reluctance motor, in particular a synchronous reluctance machine with a segmented stator.

[0053] The Fig. 5 to 7 show a variant for a joint cutter as a material cutting device.

[0054] The joint cutter shown there is essentially the same as the joint cutter of the Fig. 1 to 4 In the example shown, however, the battery 18 is permanently installed. Furthermore, the converter 19 is also located in the lower area of ​​the chassis 1.

[0055] The structure of the electric motor 12, however, is identical to that of the Fig. 1 to 4 .

[0056] In particular, the arrangement of the battery 18 above the clamping fixture 11 and the coaxially arranged rotor 13 causes the mass of the battery 18 to press the cutting disc 10 downwards into the material to be cut during operation of the floor saw. The cutting disc 10 itself causes an upward tendency due to the rotational movement of the cutting disc (arrow direction in Fig. 5 ) and the friction against the material to be cut. This upward movement is counteracted by the weight of the battery 18 and the converter 19.

[0057] Fig. 8 shows a schematic representation of a circular saw as another example of a material cutting device.

[0058] The circular saw has a saw table 30 in which a saw disk 31 serving as a cutting tool is rotatably held by means of a tool holder (disk holder) not shown.

[0059] The tool holder is driven directly by an electric motor arranged coaxially to the tool holder, with a rotor 13 and a stator 14.

[0060] In this example, the stator 14 is also designed as a segmented stator 14 and surrounds the rotor 13 over an angle of less than 360°. In the example shown by Fig. 8 the stator 33 extends over an angle of approximately 180°, analogous to the stator of the Fig. 1 and 2 .

[0061] This embodiment also ensures that the tool holder with the saw disk 31 can be driven directly coaxially by a motor without the electric motor impairing or reducing the usable cutting height (free area of ​​the saw disk 31 above the saw table 30).

Claims

1. Material cutting apparatus, comprising - a rotatably mounted tool holder (11), configured to carry a cutting tool (10); and comprising - a drive for rotating the tool holder (11); wherein - the drive has an electric motor (12), including a rotor (13) and a stator (14); - the axis of rotation of the rotor (13) of the electric motor (12) and the axis of rotation of the tool holder (11) are arranged coaxially; and wherein - the stator (14) encloses the rotor (13) over an angle of less than 360 degrees, characterised in that the electric motor (12) is arranged on the axis of rotation of the tool holder (11) such that the tool holder (11) can be driven directly by the rotor (13).

2. Material cutting apparatus as claimed in claim 1, wherein the stator (14) encloses the rotor (13) over an angle of 270° or less, 180° or less, 120° or less or 90° or less.

3. Material cutting apparatus as claimed in any one of the preceding claims, wherein - the stator (14) extends over an angle of such a size that the stator (14) extends exclusively on one side of a boundary surface (17); and wherein - the boundary surface (17) is defined as a virtual tangential surface on an outer side of the tool holder (11).

4. Material cutting apparatus as claimed in any one of the preceding claims, wherein the boundary surface (17) is a virtual horizontal plane which is defined as a tangential surface on an underside of the tool holder (11) when the material cutting apparatus is in an intended working position.

5. Material cutting apparatus as claimed in any one of the preceding claims, wherein - the tool holder (11) is substantially rotationally symmetrical; - the tool holder (11) has a maximum radius; and wherein - in a downward direction and in a forward direction the stator (14) does not extend beyond the maximum radius of the tool holder (11) when the material cutting apparatus is in an intended working position.

6. Material cutting apparatus as claimed in any one of the preceding claims, wherein the material cutting apparatus is a joint cutting apparatus, comprising - a chassis (1); and comprising - at least one running gear unit (3) for moving the chassis (1); wherein - the electric motor (12) and the tool holder (11) are arranged in a front region of the chassis (1) as seen in a main direction of travel; and wherein - an electric energy storage device (18) is provided in order to supply the electric motor (12) with electric energy.

7. Material cutting apparatus as claimed in claim 6, wherein the centre of gravity of the electric energy storage device (18) is arranged above the axis of rotation of the tool holder (11).

8. Material cutting apparatus as claimed in claim 6 or 7, wherein - a battery holder is provided in order to hold the electric energy storage device (18); and wherein - the electric energy storage device (18) is replaceable.

9. Material cutting apparatus as claimed in one of claims 6 to 8, wherein - the chassis (1) has, with respect to an intended working position, a lower region at the level of the electric motor (12) and the tool holder (11); and wherein - the chassis (1) has an upper region which is arranged above the lower region and is spaced apart at least 400 mm from the lower region.

10. Material cutting apparatus as claimed in any one of claims 6 to 9, wherein a converter device (19) is provided in the upper region or in the lower region in order to convert an electric direct current from the electric energy storage device (18) into a current suitable for operating the electric motor (12).