Soil Compacting Device Having an Electric Drive

Abstract

A soil compacting device includes an upper mass and a lower mass which is coupled to the upper mass by a spring. The lower mass is movable relative to the upper mass and comprises a ground contact element for soil compaction. A drive for generating a working movement of the ground contact element is provided on the upper mass, the drive has a tamping device and an electric motor for driving the tamping device. The tamping device has a crank wheel that can be driven in rotating manner by the electric motor, a connection rod coupled to the crank wheel, and a tamping piston which can be moved in reciprocating fashion and is coupled to the connection rod and which interacts with the spring. The electric motor has a stator and a rotor. The rotor is rigidly or elastically coupled to the crank wheel.

Claims

1. A soil compacting device, comprising: an upper mass; and a lower mass which is coupled to the upper mass by a spring and which is movable relative to the upper mass, wherein the lower mass comprises a ground contact element for soil compaction; wherein a drive for generating a working movement of the ground contact element is provided on the upper mass; the drive has a tamping device and an electric motor for driving the tamping device; the tamping device has: a crank wheel that can be driven in rotating manner by the electric motor, a connection rod coupled to the crank wheel, and a tamping piston, which can be moved in a reciprocating fashion, which is coupled to the connection rod, and which interacts with the spring; the electric motor has a stator and a rotor; and wherein the rotor is rigidly or elastically coupled to the crank wheel.

2. The soil compacting device according to claim 1, wherein the rotor is formed on a circumference of the crank wheel.

3. The soil compacting device according to claim 2, wherein the rotor has a plurality of rotor poles which are arranged on the circumference of the crank wheel.

4. The soil compacting device according to claim 3, wherein the rotor poles are laminated.

5. The soil compacting device according to claim 4, wherein the rotor poles are laminated together with the crank wheel.

6. The soil compacting device according to claim 3, wherein the crank wheel is embodied in non-laminated fashion and carries the laminated rotor poles on its circumference.

7. The soil compacting device according to claim 1, wherein the stator encloses the rotor over an angle of less than 360 degrees.

8. The soil compacting device according to claim 1, wherein, in an intended working position of the soil compacting device, the stator is arranged above the rotor.

9. The soil compacting device according to claim 1, wherein at least two crank wheels are provided on a circumference of each a rotor; and wherein the connection rod is driven jointly by the at least two crank wheels.

10. The soil compacting device according to claim 1, wherein at least part of the drive is enclosed by a drive housing; and wherein an air flow generating device is provided for generating a flow of cooling air within the drive housing to cool the rotor and the stator.

11. The soil compacting device according to claim 1, wherein the air flow generating device has at least one of the following operating principles: by the movement of the tamping piston, an air pump effect can be generated for generating the flow of cooling air; at least one fan blade is provided on the rotor for generating the flow of cooling air.

12. The soil compacting device according to claim 1, wherein an air inlet for the inflow of air from the environment and an air outlet for releasing air to the environment are provided on the drive housing; a check valve is provided in the air inlet for setting an air flow direction from the environment into the drive housing; and wherein a check valve is provided in the air outlet for setting an air flow direction from the drive housing into the environment.

13. The soil compacting device according to claim 1, wherein a motor controller is provided for controlling the electric motor in such a way that the speed of the rotor, and thus the speed of the crank wheel, are variable over one or more revolutions of the rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] These and other advantages and features of the invention are explained in more detail below using examples with the aid of the accompanying figures. In the figures:

[0041] FIG. 1 shows a vibration tamper known from the prior art as a soil compacting device;

[0042] FIG. 2 shows a vibration tamper as a soil compacting device according to an embodiment the invention in a sectional side view and front view

[0043] FIG. 3 shows different variants of a vibration tamper according to an embodiment of the invention in a sectional front view;

[0044] FIG. 4 shows further variants of a vibration tamper according to embodiments of the invention;

[0045] FIG. 5 shows a variant of a vibration tamper with a rigid coupling of rotor and crank wheel;

[0046] FIG. 6 shows a vibration tamper with an air flow generating device;

[0047] FIG. 7 shows a variant of an air flow generating device;

[0048] FIG. 8 shows another embodiment of an air flow generating device;

[0049] FIG. 9 shows a vibrating tamper with a retractable handle; and

[0050] FIG. 10 shows a variant of a vibration tamper according to the invention.

DETAILED DESCRIPTION

[0051] FIG. 2 shows a vibration tamper as a soil compacting device according to the invention, in a lateral sectional view in the left part of the picture and in a sectional front view in the right part of the picture. As far as components correspond functionally to the components of the vibration tamper of FIG. 1 explained above in connection with the prior art, the same reference numerals are used.

[0052] 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 mechanism, or simply, spring controller 3. Spring controller 3 supports a spring-mass system, in which a forced movement (linear reciprocating movement of the tamping piston) initiated via upper mass 1 causes a spring-action tamping movement of a ground contact plate 4 provided on lower mass 2.

[0053] A handle controller 11, e.g., a handlebar, is attached to upper mass 1 via a vibration decoupling controller 12, for example rubber buffers. An operator can guide the vibration tamper with his/her hands on handle controller 11. An energy storage controller in the form of a rechargeable battery 13 is attached to handle controller 11.

[0054] Inside upper mass 1, provision is made for an electric motor 20, comprising a stator 21 and a rotor 22. Electric motor 20 is embodied as a synchronous reluctance machine, with stator 21 being a segmented stator, which only extends over a range of approximately 90°, as can be seen in the right-hand part of FIG. 2.

[0055] Rotor 22 is arranged on the outer circumference of a crank wheel 23. In this way, crank wheel 23 is an integral part of electric motor 20 and is driven directly by it without a gear being interposed.

[0056] Rotor 22 can be designed slightly wider than the thickness of crank wheel 23, as can be seen in the left-hand part of FIG. 2, where rotor 22 slightly arches over crank wheel 23.

[0057] Crank wheel 23 drives a connection rod 25 via a crank pin 24, which connection rod 25 in turn causes a tamping piston 26 to move in a linear reciprocating fashion in a manner known per se. Tamping piston 26 interacts with spring controller 3 in order to achieve a spring-action tamping movement of ground contact plate 4 from the guided reciprocating movement of tamping piston 26.

[0058] Rechargeable battery 13 is also provided on upper mass 1 on handle controller 11, which is connected to upper mass 1 via vibration decoupling device 12. Rechargeable battery 13 serves to supply electric motor 20 with energy.

[0059] Rotor 22 is embodied in laminated fashion and, accordingly, has a laminated core which is fastened to or carried by crank wheel 23, which is embodied, for example, as a rotary part or a forged part. In one variant, it is possible that rotor 22 and crank wheel 23 are formed together by stacked sheet metals, i.e., they are embodied in a laminated fashion.

[0060] FIG. 3 shows different variants of the tamper from FIG. 2, each with differently configured rotors 22 with differently configured rotor poles. In particular, it can be seen in the different variants a to f of FIG. 3 that the rotors have different numbers of rotor poles.

[0061] In particular, the different variants have the following features: [0062] a: combination crank wheel with synchronous reluctance ring motor [0063] b: synchronous reluctance rotor as a crank wheel [0064] c: crank wheel with magnets arranged on the circumference [0065] d: crank wheel with magnets arranged on the circumference and/or on the inside [0066] e: crank wheel as an asynchronous motor rotor; also, possible as a combination [0067] f: salient poles in asynchronous, magnetic or synchronous reluctance motors

[0068] In the left-hand part a, FIG. 4 shows 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. Crank wheels 23 drive jointly connection rod 25. A particularly compact and powerful drive can be implemented due to the double motor arrangement.

[0069] In the variant of FIG. 4b, rotor 22 is arranged axially offset with respect to crank wheel 23. This allows the weight distribution along the tamping axis to be optimally designed.

[0070] FIG. 5 shows another embodiment as a variant to that of FIG. 4b. Here, rotor 22 and crank wheel 23 are arranged coaxially on a common shaft 27 and coupled to one another by a shaft-hub connection (here: feather key connection) in a form-fitting manner at least in the circumferential direction.

[0071] FIG. 6 shows a vibration tamper similar to that of FIG. 2.

[0072] In addition, it is illustrated that tamping piston 26 together with spring controller 3 forms a kind of air pump, which compresses and decompresses at intervals the air inside a drive housing 28 enclosing electric motor 20, crank wheel 23 and parts of the tamping device.

[0073] The air is moved inside drive housing 28 as a result of the alternating compression and relief, as a result of which a flow of cooling air is created, which cools the components of electric motor 20.

[0074] FIG. 7 shows another embodiment with an air flow generating device having fan blades 29, which are arranged on rotor 23 and crank wheel 23, respectively. Due to the rotation of rotor 22 and crank wheel 23, the air inside the drive housing 28 is circulated, resulting in a cooling effect.

[0075] FIG. 8 shows a further variant of the air flow generating device.

[0076] The principle is based on the illustration in FIG. 6, so that the linear movement of lower mass 2 with spring controller 3 achieves a pumping effect inside drive housing 28. Drive housing 28 has an air inlet 30 and an air outlet 31. Air inlet 30 communicates with a first check valve 32 (inlet check valve 32) via an air duct 30a. An outlet check valve 33 is provided at air outlet 31.

[0077] FIG. 8 also shows that air is guided over rechargeable battery 13 via air duct 30a extending between inlet check valve 32 and air inlet 30, and thus the air initially cools rechargeable battery 13 until the air enters the interior of drive housing 28.

[0078] Due to the alternating positive and negative pressures inside drive housing 28 during the tamping movement of lower mass 2, air is alternately sucked into drive housing 28 via inlet check valve 32 and air inlet 30 and is expelled via air outlet 31 and outlet check valve 33. A constant flow of cooling air inside drive housing 28 can thus be brought about by the pumping movement of lower mass 2.

[0079] FIG. 9 shows an example of a tamping device according to an embodiment of the invention comprising a retractable handlebar 34, with handlebar 34 depicted in the left-hand part of FIG. 9 in a retracted position, e.g. a particularly compact transport position, while being depicted in the right-hand part of the figure in the unfolded position, namely the operating or working position.

[0080] Rechargeable battery 13 can be connected to the drive housing 28 via an elastic hose serving as an air duct 30a to enable the flow of cooling air in the manner described above and to allow the handlebar to be unfolded.

[0081] FIG. 10 shows a variant of vibration tamper of FIG. 2. In this case, stator 21 is pivoted by 90° in the direction of the axis of rotation of rotor 22, i.e., relative to rotor 22 and thus also to crank wheel 23. In this way the construction height of drive housing 28 and thus of the entire tamper can be reduced.

[0082] Air duct 30a extending at least between the housing of rechargeable battery 30 and drive housing 28 should have a certain elasticity in all variants shown, in particular also in the variants of FIGS. 2, 4, 8 and 10, to be able to compensate a relative movement of handle controller 11 carrying rechargeable battery 13 relative to the drive housing 28 of upper mass 1.