EP4180579A1 - Soil compacting device with electric drive - Google Patents

Abstract

A soil compacting device is specified, having an upper mass (1) and a lower mass (2) which can be moved relative to the upper mass (1) and is coupled to the upper mass (1) via a spring device (3), with a soil contact element (4) for soil compaction, a drive for generating a working movement of the ground contact element being provided on the upper mass (1), the drive having a tamping device and an electric motor (20) for driving the tamping device and the tamping device having: a crank wheel (23 ), a connecting rod (25) coupled to the crank wheel (23) and a ramming piston (26) which can be moved back and forth and is coupled to the connecting rod (25) and which interacts with the spring device (3). The electric motor (20) has a stator (21) and a rotor (22), the rotor (22) being rigidly or elastically coupled to the crank wheel (23). In particular, the rotor (22) is formed on the circumference of the crank wheel (23).

Description

The invention relates to a soil compacting device with an electric drive.

Such a soil compacting device, in particular a so-called vibration tamper or vibratory tamper, is widely known and is used for compacting soils and asphalt layers. The rammers are driven in many ways by internal combustion engines, e.g. two-stroke engines. It is also known to provide electric drive motors.

With an electric drive, the electric motor is usually operated at a higher speed and drives a spring-mass system via a reduction gear, which serves as a ramming system. The electric drive motor is fed either from the electrical power supply or from rechargeable batteries that are carried along.

The electric drive motors have a stator and a rotor. Asynchronous machines with squirrel-cage rotors and brushless direct current motors (BLDC motors) have proven to be suitable.

Due to the design of the drive motors and the mode of operation of a vibratory rammer, a reduction gear is required to adjust the speeds (ramp frequency) required by the rammer. Such a transmission requires space and additional components. In addition, it reduces the efficiency of the drive, which has a disadvantageous effect primarily due to the limited electrical capacity of the batteries that can be used.

1 shows an example of a vibration tamper known from the prior art, with an upper mass 1 and a lower mass 2 that is movable relative to the upper mass 1 and is coupled to the upper mass 1 via a spring device 3 . The spring device 3 supports a spring-mass system in which a forced movement initiated via the upper mass 1 causes a spring-loaded pitching movement of a ground contact plate 4 provided on the lower mass 2 .

An electric motor 5 is provided on the upper mass 1 and drives a crank wheel 7 in rotation via a reduction gear 6 . A crank pin 8 is provided on the crank wheel 7 and is coupled to a connecting rod 9 . The connecting rod 9 in turn is coupled to a ramming piston 10, the end of which interacts with the spring device 3 in a manner known per se.

A handle device 11, e.g. a handle bar, is attached to the upper mass 1 via a vibration decoupling device 12, e.g. An operator can guide the vibratory rammer with his hands on the handle device 11 .

An energy storage device in the form of a rechargeable battery 13 is attached to the handle device 11 .

At the in 1 In the embodiment of a conventional vibrating rammer shown, the battery 13 is coupled to the electric motor 5, not only to route the electrical supply lines to the electric motor 5, but also to route a flow of cooling air over the battery 13 and the electric motor 5. The flow of cooling air can be generated by a blower, not shown, for example by a fan provided on the electric motor 5 .

In order to be able to accommodate the various components on the rammer, the drive motor must generally be arranged outside of the rammer axis, so that tilting moments occur during operation of the rammer, which reduce the effect of the rammer and worsen the manageability.

The invention is based on the object of specifying a soil compacting device that serves as a vibratory tamper, which enables a particularly compact design with the smallest possible number of components.

The object is specified according to the invention by a soil compacting device having the features of claim 1 . Advantageous configurations are specified in the dependent claims.

A soil compacting device is specified, with an upper mass and with a lower mass that can be moved relative to the upper mass and is coupled to the upper mass via a spring device, with a soil contact element for soil compaction, with a drive for generating a working movement of the soil contact element being provided on the upper mass. The drive has a ramming device and an electric motor for driving the ramming device, the ramming device having: a crank wheel that can be driven in rotation by the electric motor, a connecting rod coupled to the crank wheel, and a ramming piston that can be moved back and forth and that is coupled to the connecting rod Spring device interacts. In this case, the electric motor has a stator and a rotor, the rotor being rigidly or elastically coupled to the crank wheel.

The rotor and the crank wheel thus form a unit. A relative rotation between rotor and crank wheel is - apart from permissible elasticity, e.g. with an elastic coupling - not possible. There is also no gear between the rotor and the crank wheel, in particular no reduction gear, as is required in the prior art.

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

Due to the direct coupling of rotor and crank wheel, the otherwise interposed reduction gear is unnecessary, so that a considerable number of components can be saved. With an appropriate design of the electric motor, it is possible to operate the electric motor at a low speed, which is already suitable for the pitching process and the desired pitching frequency. Accordingly, the electric motor must provide sufficient torque at this low speed in order to be able to powerfully carry out the pitching process. A reluctance machine is particularly suitable here.

The omission of the reduction gear allows a particularly compact construction of the soil compacting device, which also allows a favorable weight or mass distribution of the components. With a corresponding design of the electric motor and the ramming device, it is possible that the center of gravity of the electric motor is arranged on the ramming axis, ie on the longitudinal axis of the movement of the lower mass and the ramming piston. There is then no leverage between the movement of the lower mass and the center of gravity of the electric motor. As a result, undesired tilting moments can be avoided during operation of the rammer.

The rotor can be formed on the circumference of the crank wheel. In this embodiment, the rotor is more or less replaced by the crank wheel or it becomes part of the crank wheel. In this way, the rotor and crank wheel can be integrated into one part. In this case, the rotor can be arranged radially on the outside on the circumference of the crank wheel. Crank wheel and rotor form a unit, so that the rotor can take over the function of the crank wheel, i.e. in particular driving or moving the connecting rod. A classic motor shaft for connecting the rotor and crank wheel is no longer necessary.

The outer circumference of the crank wheel must be suitably designed to serve as a rotor.

The rotor can thus have a plurality of rotor poles which can be arranged on the circumference of the crank wheel.

The rotor poles can be laminated, that is to say form a laminated core in the form of laminated sheets stacked on top of one another. For electromagnetic reasons, laminated structures are to be provided for the rotor, so that the rotor poles and the pole wheel formed thereby are to be formed by layered laminations.

The rotor poles can be laminated together with the crank wheel. This means that the rotor poles and the crank wheel together consist of stacked laminations. For example, a metal sheet can include the contour of the rotor poles on the circumference and the crank wheel on the inside. The rotor with the rotor poles and the crank wheel are formed by stacking and assembling the laminations. The sheets can be held together in a suitable way, e.g. by pin connections (interference fits) or screw connections.

In one variant, the crank wheel can be designed without laminations and carry the laminated rotor poles, ie the laminated magnet wheel, on its circumference. Accordingly, the crank wheel can be solid, e.g. as a turned part (steel turned part or cast turned part). It serves as a carrier for the rotor with the rotor laminations and carries the layered laminations for the rotor poles on the circumference. Accordingly, the laminated core ring is attached to the circumference of the crank wheel.

The stator can enclose the rotor over an angle of less than 360°. In this variant, the motor stator can no longer be designed as a closed rotary 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 can extend over an angle of, for example, 270° or less, 180° or less, 120° or less, or 90° or less.

Accordingly, it is also possible to distribute a plurality of stator segments or stator blocks on the circumference of the rotor, as a result of which the performance of the motor and in particular the torque of the motor can be increased.

When the soil compacting device is in an intended working position, the stator can be arranged above the rotor. For example, the stator can be held in the engine cover or in the cover of the drive housing or crankcase. He does not have to have a structural unit with the rotor. In particular, the stator and rotor do not have to be housed separately from the crank wheel in a common electric motor housing. Rather, the stator, rotor and crank wheel can be arranged in a common housing or separately from one another.

In a variant, at least two crank wheels can be provided, on the circumference of which a rotor is provided in each case, with the connecting rod being driven jointly by the two crank wheels. Accordingly, several rotors and stators can also be provided in this embodiment, as a result of which a particularly powerful drive of the ramming device is possible.

In particular, the two crank wheels and the associated rotors can be aligned coaxially with one another in order to be able to drive the connecting rod in the desired manner.

At least part of the drive may be enclosed by a drive housing, and an air flow generating device may be provided for generating a flow of cooling air within the drive housing to cool the rotor and stator. The drive housing can accordingly also be understood as a crankcase or as a motor housing, with the stator, the rotor, the crank wheel and at least part of the connecting rod and possibly also part of the ram piston being accommodated inside the drive housing.

With the help of the air flow generating device, it is possible to generate a cooling air flow inside the drive housing and thus to dissipate heat from the rotor and stator, but possibly also from the tamping device.

The air flow generating device can have at least one of the following operating principles: An air pump effect can be generated by the movement of the ramming piston, for generating the cooling air flow, or: on the rotor at least one fan blade can be provided for generating the cooling air flow. The ramming piston on the one hand and the rotor on the other hand thus have effective surfaces that specifically generate an air movement that can form or support the desired flow of cooling air.

An air inlet for the inflow of air from the environment and an air outlet for discharging air into the environment can be provided on the drive housing, wherein a non-return valve can be provided in the air inlet for specifying a direction of air flow from the environment into the drive housing, and in the air outlet a non-return valve can be provided for specifying an air flow direction from the drive housing into the environment.

The non-return valve is therefore a directional valve that only allows air to flow in one direction, namely either into the drive housing via the air inlet or out of the drive housing via the air outlet. The non-return valve can, for example, have a rubber flap-like element which, depending on the air flow direction, opens or closes a relevant opening.

In connection with the pumping effect when the ramming piston moves and thus a change in the air volume inside the drive housing, fresh air from the environment can be sucked into the drive housing via the air inlet and expelled via the air outlet when the ramming piston has a compressing effect. As a result, a constant exchange of air inside the drive housing and thus a cooling effect can be achieved.

A motor control device can be provided for controlling the electric motor in such a way that the speed of the rotor and thus of the crank wheel can be changed over one or more revolutions of the rotor. The engine control device is thus used for a targeted change in the speed and thus the torque. This change is therefore based not only on a reaction of the tamping system and thus of the soil to be compacted, but on a targeted activation by the engine control device.

In this way, a variation of the movement of the tamping foot is possible, which can be used, for example, to dynamize the tamping process, but also to calm the machine. For example, in cases where the tamping device jumps on a hard ground, the drive power of the motor can be reduced and the tamping device can thereby be quieted.

It is also possible to apply a double impact of the tamping device to the soil to be compacted by briefly increasing the speed. This can also result in the recoil forces acting on the operator guiding the ramming device being able to be reduced, with high ramming energy at the same time.

The motor controller can also be used to scale the torque to apply different intensities of impact to the ground.

Fig. 1

einen aus dem Stand der Technik bekannten Vibrationsstampfer als Bodenverdichtungsvorrichtung;

Fig. 2

einen Vibrationsstampfer als erfindungsgemäße Bodenverdichtungsvorrichtung in geschnittener Seitenansicht und Vorderansicht;

Fig. 3

verschiedene Varianten eines erfindungsgemäßen Vibrationsstampfers in geschnittener Vorderansicht;

Fig. 4

weitere Varianten eines erfindungsgemäßen Vibrationsstampfers;

Fig. 5

eine Variante eines Vibrationsstampfers mit einer starren Kopplung von Rotor und Kurbelrad;

Fig. 6

einen Vibrationsstampfer mit Luftstromerzeugungsvorrichtung;

Fig. 7

eine Variante einer Luftstromerzeugungsvorrichtung;

Fig. 8

eine andere Ausführungsform einer Luftstromerzeugungsvorrichtung;

Fig. 9

einen Vibrationsstampfer mit anlegbarer Griffeinrichtung; und

Fig. 10

eine Variante eines erfindungsgemäßen Vibrationsstampfers.

These and other advantages and features of the invention are explained in more detail below using examples with the aid of the accompanying figures. Show it:

1

a vibratory tamper known from the prior art as a soil compacting device;

2

a vibration tamper as a soil compaction device according to the invention in a sectional side view and front view;

3

different variants of a vibration tamper according to the invention in a sectional front view;

4

further variants of a vibration tamper according to the invention;

figure 5

a variant of a vibration rammer with a rigid coupling of rotor and crank wheel;

6

a vibratory tamper with airflow generating device;

7

a variant of an air flow generating device;

8

another embodiment of an airflow generating device;

9

a vibratory rammer with attachable grip means; and

10

a variant of a vibratory tamper according to the invention.

2 shows a vibration tamper as a soil compacting device according to the invention, in the left part of the picture in a lateral sectional view and in the right part of the picture in a sectional view from the front. As far as components functionally the components of the vibratory tamper explained above in connection with the prior art 1 correspond, the same reference numerals are used.

Accordingly, the vibration tamper has an upper mass 1 and a lower mass 2 that is movable relative to the upper mass 1 and is coupled to the upper mass 1 via a spring device 3 . The spring device 3 supports a spring-mass system in which a forced movement introduced via the upper mass 1 (linear back and forth movement of the ramming piston) causes a resilient ramming movement of a ground contact plate 4 provided on the lower mass 2 .

A handle device 11, e.g. a handle bar, is attached to the upper mass 1 via a vibration decoupling device 12, e.g. An operator can guide the vibratory rammer with his hands on the handle device 11 . An energy storage device in the form of a rechargeable battery 13 is attached to the handle device 11 .

An electric motor 20 is provided inside the upper mass 1, with a stator 21 and a rotor 22. The electric motor 20 is designed as a synchronous reluctance machine, with the stator 21 being a segmented stator which only extends over a range of approx extends, as in the right part of the picture 2 recognizable.

The rotor 22 is arranged on the outer circumference of a crank wheel 23 . In this way, the crank wheel 23 is an integral part of the electric motor 20 and is driven directly by it, without a gearbox being interposed.

The rotor 22 can be made slightly wider than the thickness of the crank wheel 23, as in the left part of FIG 2 recognizable where the rotor 22 arches over the crank wheel 23 somewhat.

The crank wheel 23 drives a connecting rod 25 via a crank pin 24, which in turn causes a ramming piston 26 to perform a linear reciprocating motion in a manner known per se. The ramming piston 26 interacts with the spring device 3 in order to achieve a resilient ramming movement of the ground contact plate 4 from the guided reciprocating movement of the ramming piston 26 .

The rechargeable battery 13 is also provided on the upper mass 1 on the handle device 11 , which is connected to the upper mass 1 via the vibration decoupling device 12 . The rechargeable battery 13 serves to supply the electric motor 20 with energy.

The rotor 22 is laminated and accordingly has a laminated core which is fastened to or carried by the crank wheel 23, which is e.g. a turned part or a forged part. In one variant, it is possible for the rotor 22 and the crank wheel 23 to be formed together by layered metal sheets, that is to say they are made of metal sheets.

3 shows different variants of the rammer from 2 each with differently designed rotors 22 with differently designed rotor poles. In particular, with the different variants a to f of 3 recognizable that the rotors have different numbers of rotor poles.

1. a: Kombination Kurbelrad mit Synchron-Reluktanz-Ringmotor
2. b: Synchron-Reluktanz-Rotor als Kurbelrad
3. c: Kurbelrad mit am Umfang angeordneten Magneten
4. d: Kurbelrad mit am Umfang und/oder innen angeordneten Magneten
5. e: Kurbelrad als Asynchronmotor-Rotor; auch als Kombination möglich
6. f: ausgeprägte Pole bei Asynchron-, Magnet-oder Synchron-Reluktanz-Motoren

In detail, the different variants have the following special features:

1. a: Combination crank wheel with synchronous reluctance ring motor
2. b: Synchronous reluctance rotor as a crank wheel
3. c: Crank wheel with magnets arranged on the circumference
4. d: Crank wheel with magnets arranged on the circumference and/or on the inside
5. e: crank wheel as asynchronous motor rotor; also possible as a combination
6. f: salient poles in asynchronous, magnet or synchronous reluctance motors

4 shows in the left part a a variant in which two crank wheels 23 are driven by rotors 22 arranged on the circumference. Accordingly, two electric motors 20 arranged coaxially to one another are provided. The crank wheels 23 drive the connecting rod 25 together. Due to the double motor arrangement, a particularly compact and powerful drive can be implemented.

In the variant of Figure 4b the rotor 22 is arranged axially offset to the crank wheel 23 . This allows the weight distribution along the ramming axis to be optimally designed.

figure 5 shows another embodiment as a variant to that of FIG Figure 4b . Here, the rotor 22 and the crank wheel 23 are arranged coaxially to one another on a common shaft 27 and are connected by a shaft-hub connection (here: feather key connection) at least positively coupled to each other in the circumferential direction.

6 shows a vibratory rammer similar to that of 2 .

It is also clear that the ramming piston 26 together with the spring device 3 forms a type of air pump that periodically compresses and decompresses the air inside a drive housing 28 enclosing the electric motor 20, the crank wheel 23 and parts of the ramming device.

The air is moved inside the drive housing 28 as a result of the alternating compression and relief, as a result of which a cooling air flow is created which cools the components of the electric motor 20 .

7 FIG. 12 shows another embodiment with an air flow generating device that has fan blades 29 that are arranged on the rotor 23 or the crank wheel 23. FIG. The rotation of the rotor 22 and the crank wheel 23 circulates the air inside the drive housing 28, resulting in a cooling effect.

8 shows a further variant of the air flow generating device.

The principle is based on the representation of 6 , so that a pumping effect inside the drive housing 28 is achieved by the linear movement of the lower mass 2 with the spring device 3 . The drive housing 28 has an air inlet 30 and an air outlet 31 . The air inlet 30 communicates with a first check valve 32 (inlet check valve 32) via an air passage 30a. An outlet check valve 33 is provided at the air outlet 31 .

In 8 also shows that air is guided via the air duct 30a extending between the inlet non-return valve 32 and the air inlet 30 over the battery 13 and the air thus initially cools the battery 13 until the air reaches the interior of the drive housing 28.

Due to the alternating positive and negative pressures inside the drive housing 28 during the pitching movement of the lower mass 2, air is alternately sucked into the drive housing 28 via the inlet check valve 32 and the air inlet 30 and via the air outlet 31 and the outlet check valve 33 driven out. A constant flow of cooling air inside the drive housing 28 can thus be brought about by the pumping movement of the lower mass 2 .

9 shows an example of a tamping device according to the invention with a foldable handlebar 34, wherein in the left part of the picture 9 the handle bar 34 is shown in the folded-down position, for example a particularly compact transport position, while it is shown in the right-hand part of the picture in the folded-out position, namely the operating or working position.

The rechargeable battery 13 can be connected to the drive housing 28 via an elastic hose 35 serving as an air duct 30a in order to enable the cooling air to be guided in the manner described above and to allow the handle bar 34 to be folded down.

10 shows a variant of the vibratory tamper from 2 . The stator 21 is pivoted by 90° in the direction of the axis of rotation of the rotor 22, i.e. relative to the rotor 22 and thus also to the crank wheel 23. In this way, the overall height of the drive housing 28 and thus of the entire tamper can be reduced.

The at least between the housing of the battery 30 and the drive housing 28 extending air duct 30a should be in all variants shown, especially in the variants of 2 , 4 , 8th and 10 , have a certain elasticity in order to be able to compensate for a relative movement of the grip device 11 carrying the rechargeable battery 13 relative to the drive housing 28 of the upper mass 1 .

Claims (13)

Soil compaction device, with - An upper mass (1); and with - A lower mass (2) which is movable relative to the upper mass (1) and is coupled to the upper mass (1) via a spring device (3) and has a soil contact element (4) for soil compaction; whereby - A drive for generating a working movement of the ground contact element is provided on the upper mass (1); - The drive has a tamping device and an electric motor (20) for driving the tamping device; - the tamping device has: a crank wheel (23) which can be driven in rotation by the electric motor (20), a connecting rod (25) coupled to the crank wheel (23) and a ramming piston (26) which is coupled to the connecting rod (25) and can be moved back and forth, which interacts with the spring device (3); - The electric motor (20) has a stator (21) and a rotor (22); and where - The rotor (22) is rigidly or elastically coupled to the crank wheel (23). A soil compacting device according to claim 1, wherein the rotor (22) is formed on the periphery of the crank wheel (23). A soil compacting device according to claim 1 or 2, wherein the rotor (22) has a plurality of rotor poles arranged on the circumference of the crank wheel (23). A soil compaction device according to any one of the preceding claims, wherein the rotor poles are laminated. A soil compaction device according to any one of the preceding claims, wherein the rotor poles are laminated together with the crank wheel (23). Ground compacting device according to one of the preceding claims, in which the crank wheel (23) is not laminated and carries the laminated rotor poles on its circumference. A soil compaction device according to any one of the preceding claims, wherein the stator (21) encloses the rotor (22) over an angle of less than 360 degrees. Soil compacting device according to one of the preceding claims, wherein the stator (21) is arranged above the rotor (22) when the soil compacting device is in an intended working position. Ground compaction device according to any one of the preceding claims, wherein - At least two crank wheels (23) are provided, on the circumference of which a rotor (22) is provided; and where - The connecting rod (25) is driven jointly by the two crank wheels (23). Ground compaction device according to any one of the preceding claims, wherein - At least part of the drive is enclosed by a drive housing (28); and where - An air flow generating device is provided for generating a cooling air flow within the drive housing (28) for cooling the rotor (22) and the stator (21). Ground compacting device according to one of the preceding claims, wherein the air flow generating device has at least one of the following operating principles: - An air pump effect can be generated by the movement of the ramming piston (26) in order to generate the cooling air flow; - At least one fan blade (29) is provided on the rotor (22) for generating the flow of cooling air. Ground compaction device according to any one of the preceding claims, wherein - An air inlet (30) for the inflow of air from the environment and an air outlet (31) for discharging air into the environment are provided on the drive housing (28); - A check valve (32) is provided in the air inlet (30) for specifying an air flow direction from the environment into the drive housing (28); and where - A check valve (33) is provided in the air outlet (31) for specifying an air flow direction from the drive housing (28) into the environment. Soil compaction device according to one of the preceding claims, wherein a motor control device is provided for controlling the electric motor in such a way that the speed of the rotor (22) and thus of the crank wheel (23) can be changed over one or more revolutions of the rotor (22).

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