ELECTRIC WORK MACHINE WITH BATTERY COOLING

Description

[0001] The invention relates to a work machine, in particular a battery-operated construction machine with electric drive.

[0002] Battery-powered construction machinery has a drive train with an electric motor, an energy storage unit (battery), and a converter. The converter converts the current from the energy storage unit (usually direct current) into a current suitable for powering the electric motor, such as alternating current. The components must be efficiently cooled for the construction machinery to operate reliably. This is especially true for the battery, whose cells can suffer permanent damage if exposed to excessive heat, reducing not only the storage capacity but also the battery's service life.

[0003] To cool the battery and converter, it is known to install a fan impeller on the electric motor serving as the drive motor of the construction machine, which generates an airflow. The airflow can then be directed not only over the drive motor, but also over the battery and converter to ensure appropriate cooling during operation of the construction machine.

[0004] Depending on the type of construction machine, the battery and converter may be located some distance from the electric motor. In this case, the cooling air flow must be directed through cooling ducts (air ducts) so that the cooling air flow generated by the fan on the drive motor also affects the battery and converter. Depending on the length and design of the air ducts, the cooling effect on the battery and converter may be minimal.

[0005] The cooling effect is only achieved when the drive motor is running, because only then is the fan driven. In other operating situations, there is a risk of excessive heat being applied to the battery or inverter when the drive motor is not running and therefore no cooling airflow is generated.

[0006] EP 2 857 587 B1 discloses a soil compaction device with an air-cooled battery. This device includes an air conveying device with a fan wheel that can be arranged on or at a motor shaft of the drive.

[0007] The invention is based on the object of providing a work machine with improved cooling for the battery and converter.

[0008] The object is achieved by a work machine having the features of claim 1. Advantageous embodiments are specified in the dependent claims.

[0009] A work machine is specified, comprising a working device for effecting a working movement and a drive for driving the working device, wherein the drive comprises an electric working motor, an electrical energy storage device for supplying the drive motor with electrical current, and a converter device for converting the current from the energy storage device and supplying the current to the drive motor. A cooling device is provided for cooling the energy storage device and the converter device, wherein the cooling device comprises at least one fan device for generating a cooling air flow that can be guided over the energy storage device and the converter device, wherein the fan device comprises a fan and a fan motor that drives the fan, and wherein the fan motor is provided separately from the drive motor of the drive.

[0010] The working machine can be, for example, a vibratory rammer or a vibrating plate for soil compaction. Accordingly, the working movement can be a tamping or vibrating movement, which is introduced into the ground in a known, suitable manner, for example. Other construction machines can also be used as such working machines.

[0011] The energy storage device can be a rechargeable battery of a known design.

[0012] The converter device can be, for example, a frequency converter which is suitable for converting the voltage and frequency of the current supplied from the energy storage device into a current which is suitable for the operation of the electric drive motor (electric motor).

[0013] The fan may be designed as a ventilator or propeller or other device that is driven by the fan motor to produce the desired cooling air flow.

[0014] The fan motor itself can also be an electric motor. It is provided in addition to the drive motor and can be located near or away from the drive motor on the working machine.

[0015] Suitable air ducts such as hoses, pipes or suitably designed housing elements can be provided to guide the cooling air flow.

[0016] It is important that the cooling air flow can be directed over the energy storage device and the converter unit. In particular, the cooling air flow should be directed along the outer walls of the energy storage device and the converter unit, i.e., along the housing. However, it is also possible to direct the cooling air flow through the respective housings to best reach the heat-containing components and achieve effective cooling.

[0017] It is possible to install multiple fan units with multiple fans and / or fan motors to create a flexible cooling concept. The cooling device can then appropriately control the multiple fans and, for example, also control the fans individually.

[0018] The fan motor or possibly several fan motors can be supplied with electricity using the energy from the electrical energy storage device.

[0019] Depending on the design of the machine, it is possible that no cooling is provided for the actual drive motor, but that cooling is provided solely for the energy storage and converter components. Cooling of the drive motor can then be achieved inherently through convection or radiation.

[0020] The cooling air flow can be routed between the energy storage unit and the converter. Depending on the design, the cooling air flow can be directed in both directions: either first over the energy storage unit and then downstream from the energy storage unit via the converter unit, or in the opposite direction. Since the energy storage unit contains the battery's often highly heat-sensitive cells, it may be expedient to first direct the cooling air drawn in from the environment over the energy storage unit and only then, once it has absorbed the heat from the energy storage unit, over the converter.

[0021] The fan can be positioned in the cooling air flow between the energy storage device and the converter device. The fan serves to generate the cooling air flow and, depending on the flow direction, creates a suction effect or a blower effect (pushing the cooling air downstream). Positioning the fan between the energy storage device and the converter device enables a particularly compact design. At the same time, it is possible to keep the fan relatively small because both flow sides (upstream and downstream of the fan) are used to generate the cooling air flow and cool the components located there.

[0022] A ventilation control device can be provided to control the fan motor. The ventilation control device can, in particular, control the fan motor independently of the actual drive motor of the working machine. In particular, the control allows the fan motor to be switched on and off depending on the temperature and thus does not allow the fan motor to be switched on and off depending on the operation of the drive motor.

[0023] The ventilation control system can consider, for example, the ambient temperature, the temperature at or inside the converter, and / or the temperature at or inside the energy storage unit as the relevant temperature. It is also possible to regulate the fan speed depending on the temperature to avoid unnecessarily high operation of the cooling device and thus unnecessary energy consumption.

[0024] In this way, demand-based cooling of the energy storage unit and the converter device can be achieved. This prevents premature cell aging in the energy storage unit, thereby increasing the energy and power capacity of the cells.

[0025] The required power supply for the ventilation control device as well as the fan device can also be provided via the energy storage device and, if necessary, also via the converter device.

[0026] In one embodiment of the work machine, an upper mass and a lower mass can be provided, wherein the lower mass is movable relative to the upper mass, wherein the energy storage device, the converter device and the cooling device are arranged on the upper mass, and wherein a ground contact plate can be provided on the lower mass for carrying out the working movement.

[0027] This working machine can be designed, for example, as a rammer or vibrating plate. Accordingly, the working device can act between the upper and lower masses and be designed, for example, as a rammer or a vibration exciter. A spring device or a spring-damper device can be provided between the upper and lower masses to achieve vibration decoupling between the upper and lower masses and to enable relative mobility.

[0028] Depending on the design, the drive motor can be mounted on the upper mass or the lower mass. For a rammer, it is advisable to mount the drive motor on the upper mass and transfer the drive movement of the drive motor to the lower mass with the ground contact plate via a rammer device that serves as the working device.

[0029] This principle can also be implemented with a vibration plate, where the drive movement of the drive motor on the upper mass must then be transferred to the vibration exciter on the lower mass.

[0030] In one variant, the drive motor can also be mounted directly on the base mass, e.g. directly on the ground contact plate, and coupled there with a vibration exciter.

[0031] The upper mass can have a handle for guiding the work machine by a user, wherein the energy storage device and the fan device can be arranged on the handle. In this embodiment, the work machine can be designed, for example, as a rammer. The handle, e.g., a conventional handle bar, can be decoupled from the rest of the upper mass by a vibration decoupling device to protect the user grasping the handle from strong vibrations, so that the hand-arm vibrations acting on the user remain below permissible limits.

[0032] The energy storage unit and the fan unit can be attached to the handle or supported by the handle. Since the handle can be vibration-decoupled, as explained above, the energy storage unit and the fan unit are then exposed to only minimal vibration, which increases their service life and eliminates the need for additional vibration-decoupling measures. Conversely, the increased mass of the handle unit caused by the energy storage unit and the fan also contributes to better vibration reduction at the handle bar.

[0033] The converter unit can be mounted on the handle. This means that the converter, in addition to the energy storage unit and the fan, can also be supported by the handle.

[0034] A cover can be provided on the handle device, whereby the energy storage device and / or the fan device and / or the converter device can be arranged under the cover. The cover serves as protection, in particular for the energy storage device and the converter. In addition, suitable air ducts can be formed in the cover to guide the cooling air conveyed by the fan device to the components to be cooled.

[0035] The work machine can be a soil compaction device. In particular, the work machine can be a tamping device or a vibrating plate for soil compaction.

[0036] In particular, the work machine can have an upper mass and a lower mass that is movable relative to the upper mass.

[0037] An air guiding device can be provided on the upper mass, wherein the cooling air flow is guided at least partially through the air guiding device, and wherein the air guiding device carries the converter device.

[0038] In this case, the air guide device has at least two functions: guiding the cooling air flow and supporting the converter. Furthermore, it is optionally possible for the air guide device to also support and guide the fan device and / or supply lines or electrical cables that must be routed to the converter device, for example. The air guide device can thus be designed as a multifunctional component.

[0039] For example, the air guiding device can be fastened to the upper mass as a unit, so that the air guiding device can be fastened to the upper mass together with the components carried by it.

[0040] The cooling air flow can be directed at least partially through the air ducting system. However, it can also flow into or through other areas of the machine.

[0041] A vibration decoupling device can be provided between the air guide device and the upper mass. This allows the air guide device, along with the fan device (if present) and the converter device, to be attached to the upper mass in a vibration-decoupled manner from the rest of the upper mass. Suitable vibration decoupling devices include rubber buffers or foam pads.

[0042] The energy storage device can be held in a battery holder, wherein the battery holder and the air guiding device can be coupled to one another, and wherein the battery holder and the air guiding device can be jointly fastened to the upper mass in a vibration-decoupled manner by the vibration decoupling device.

[0043] The energy storage unit in the battery holder can be kept replaceable and replaced, for example, with a new energy storage unit. The battery holder and the air ducting device can be firmly mechanically connected.

[0044] The air guiding device can comprise a support structure and a cover device that can be assembled into a single unit. The support structure can be designed to support the fan device and the converter device, wherein the support structure and the cover device, when assembled, form an air duct that extends at least between the fan device and the converter device. The air duct can accordingly be used to guide the cooling air flow. The air guiding device can thus comprise two components that can be assembled into a single unit and can also serve as housing components for the air duct.

[0045] The support structure, together with the air guidance system and the converter system, can be attached to the upper mass as a single unit. This makes it possible to mount the fan system and the converter system on the support structure and then attach the support structure to the upper mass. This can also be done with the cover system already attached and installed.

[0046] The air guiding device can have an air inlet opening provided upstream of the fan device and located downstream of the energy storage device. During operation, the fan device can then draw in air through the air inlet opening, which then flows through the energy storage device, thereby cooling it. Of course, it is also possible in this case for the cooling air flow to be guided through the energy storage device or along the housing walls of the energy storage device.

[0047] The air guiding device can have a downward-facing air outlet opening provided downstream of the converter device. The downward-facing air outlet opening can also be directed diagonally downward, so that the air flow exiting there can be directed to other locations in a targeted manner. In particular, the cooling air flow exiting the air outlet opening can be directed to other components of the working machine, such as a vibration exciter or an electric drive of the vibration exciter, as explained later.

[0048] An opening can be provided in the upper mass through which the air guide device extends downwards toward the lower mass. This creates the conditions for a cooling air flow to be directed to components on the lower mass via the air guide device.

[0049] This design is particularly suitable for a work machine designed as a vibrating plate or vibrating plate.

[0050] The lower mass can have a vibration exciter arranged on the ground contact plate for generating vibrations which can be used by the ground contact plate for soil compaction, whereby the cooling air flow can exit via the air outlet opening and be guided in the direction of the vibration exciter provided on the lower mass.

[0051] The air guiding device can have an air duct section downstream of the converter device for guiding the cooling air flow toward the vibration exciter in order to cool it. In particular, a flow direction for the cooling air flow can be created toward a drive motor driving the vibration exciter, e.g., a hydraulic motor or electric motor.

[0052] A typical vibration exciter comprises the actual excitation device, e.g. with one or more unbalanced shafts each carrying an unbalanced mass, as well as a drive motor for the excitation device.

[0053] It is increasingly possible for the unbalanced shaft(s) in the excitation device to be driven directly by an electric motor. The electric motor can be mounted on the ground contact plate in a suitable manner, e.g. suspended on screw-on domes, so that it can be cooled on several sides, particularly on its underside, by the cooling air flow supplied via the air guidance device. The aim should be to ensure that the electric motor is cooled as best as possible and that, where technically possible, the cooling air flow is also guided through the interior of the motor or its motor winding. The contour of the excitation device or the motor housing of the electric motor can be shaped to ensure the best possible air flow over the motor housing or over the excitation device.

[0054] The cooling device can comprise at least two fan devices, wherein the air flows generated by the two fan devices can be combined into a common cooling air flow. The fan devices can be arranged parallel to one another and each generate individual air flows, which are then combined into a common cooling air flow via the air guiding device.

[0055] This variant makes it possible to construct the fan units relatively compact and small, while still generating an effective cooling air flow.

[0056] Upstream of the energy storage device, an intake opening for the cooling air flow can be provided on the upper surface of the upper mass. The intake opening can be directed essentially vertically upwards. The upper surface of the upper mass will be relatively well protected from dust and dirt during operation of the vibrating plate, so that comparatively little dust is drawn into the air duct system through the intake opening provided there. The intake opening can be further protected by grilles or deflector blades to reduce dust penetration.

[0057] This specifies a work machine in which fresh ambient air is drawn in at a location where the least dust is expected in the air. This air is then drawn into the energy storage device (battery) as a cooling air stream and blown onto the converter device by the fan (or multiple fan) in the air ducting device. The cross-section of the air ducts in the air ducting device is thereby changed so that the converter device experiences optimal cooling.

[0058] The air outlet of the air ducting system can be located below the upper mass. From there, the air can be directed directly to the vibration exciter and its installed motor to achieve the best possible cooling.

[0059] In this way, the cooling device provided cools all components in the machine that generate significant power losses during operation. The cooling sequence, i.e. the path of the cooling air flow, is selected such that the component with the lowest permissible temperature is cooled first (e.g. the energy storage device). The last component in the cooling air flow, on the other hand, can withstand the highest permissible temperature (e.g. the electric motor in the vibration exciter). At the same time, the air is directed in such a way that, at a maximum permissible ambient temperature of e.g. 45°C, it can precisely dissipate the power losses of the respective component it passes by. This balanced and optimized cooling performance makes it possible to use particularly low-power fans, which in turn place only low power requirements that must be satisfied by the energy storage device during operation.

[0060] With the help of the invention, it is possible to improve the thermal management of a work machine in order to avoid overheating of the battery and also of the converter and thus to protect and extend the service life of the battery.

[0061] By using fans, e.g., mounted on the handlebar in front of or below the inverter, the cooling airflow can first be drawn in via the battery and then directed through the inverter. Controlling the fan independently of the operating state of the drive motor can also enable use in warm environments, e.g., in strong sunlight.

[0062] 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 schematic side sectional view a working machine according to the invention as a vibratory rammer; Fig. 2 in schematic side view another working machine according to the invention as a vibrating plate; Fig. 3 a variant of a vibrating plate with air guidance device; and Fig. 4 a detail about the variant of Fig. 3 .

[0063] Fig. 1 schematically shows a vibratory rammer with an upper mass 1 and a lower mass 2 movable relative to the upper mass 1. The upper mass 1 and the lower mass 2 are coupled to each other by a known spring device 3. A ground contact plate 4 for soil compaction is provided on the underside of the lower mass 2.

[0064] The upper mass 1 is provided with a drive with an electric motor 5, which rotates a crank wheel 6, which is coupled to a connecting rod 8 via a crank pin 7. The connecting rod 8 is connected to a tamping piston 9, so that the rotational movement of the crank wheel 6 is converted into a reciprocating movement of the tamping piston 9. The linear movement of the tamping piston 9 is then finally transmitted via the spring device 3 to the ground contact plate 4, which executes the actual tamping movement.

[0065] To supply energy to the electric motor 5, a battery 10 serving as an electrical energy storage device is provided.

[0066] The electrical current provided by the battery 10 is converted or transformed by a converter 11, which serves as a converter device, in terms of its voltage and frequency into a current suitable for the electric motor 5. In particular, it may be possible to generate an alternating current for the electric motor 5 from the direct current stored in the battery 10.

[0067] The crank wheel 6, the crank pin 7, and the connecting rod 8 are housed in a crankcase 12, to which the electric motor 5 is also attached. In one variant, the electric motor 5 can also be arranged largely inside the crankcase 12.

[0068] On the top side of the crankcase 12, a handle device 13 is attached, which is designed as a handle bar and belongs to the upper mass 1. For vibration decoupling of the handle device 13, a vibration decoupling device 14, e.g. in the form of rubber buffers, is arranged between the handle device 13 and the crankcase 12. As a result, the handle device 13 is pivotable within certain limits relative to the remaining upper mass 1, in particular relative to the crankcase 12, in order to enable an operator who is using the handle bar or the handle device 13 as intended on the Fig. 1 right end to protect against the effects of excessive vibrations.

[0069] Both the battery 10 and the converter 11 are attached to the handle 13 or are supported by it. It is possible for the battery 10 to be removable and attached to the handle 13 so that it can be replaced with a fresh battery 10 at any time.

[0070] Spatially between the battery 10 and the converter 11, a fan device 15 is arranged, which has a fan, e.g. a ventilator, and a fan motor.

[0071] The fan device 15 generates a cooling air flow 16 by sucking in air via the battery 10 and pushing it downstream via the converter 11 until the cooling air flow 16 is released back into the environment. The course of the cooling air flow 16 is shown in Fig. 1 symbolically represented by an arrow.

[0072] To better guide the cooling air flow 16 and to protect the various components, a cover 17, e.g. a plastic hood, is provided.

[0073] In a variant not shown, the fan device 15 can also be arranged upstream of the battery 10 or downstream of the converter 11 in order to generate the cooling air flow 16 (see direction of the arrow) in a suitable manner.

[0074] Fig. 2 shows another embodiment of the working machine as a vibrating plate. Functionally similar or identical components as in the embodiment of Fig. 1 are designated by the same reference symbols.

[0075] Accordingly, the vibrating plate also has an upper mass 1 and a lower mass 2, wherein the lower mass 2 is movable relative to the upper mass 1. For this purpose, vibration decoupling elements 20 are provided between the upper mass 1 and the lower mass 2.

[0076] A ground contact plate 4 is formed on the base mass 2. The electric motor 5, which drives a vibration exciter 21, is arranged on the ground contact plate 4. The vibration exciter 21 can, for example, have one or more unbalanced shafts, which are set in rotation by the electric motor 5 serving as the drive motor in order to generate the desired vibrations. The vibrations are then introduced directly into the soil to be compacted via the ground contact plate 4.

[0077] The battery 10, which provides the energy for the electric motor 5, is arranged on the upper mass 1, together with the converter 11.

[0078] As with the embodiment of Fig. 1 The fan device 15 is arranged between the battery 10 and the converter 11 to effect the cooling air flow 16 through the battery 10 and along the converter 11. As can be seen, the cooling air flow 16 can be guided downstream of the fan device 15 in such a way that the converter 11 is surrounded by the cooling air flow 16 on as many sides as possible, or at least on both sides. Depending on the design, however, the cooling effect may also be sufficient if the battery 10 and / or converter 11 are only exposed to one side of the cooling air flow.

[0079] The cover 17 is provided to improve the guidance of the cooling air flow 16.

[0080] The handle device 13 of the vibrating plate is designed in the form of a drawbar that can be guided by an operator and is attached to the lower mass 2.

[0081] Fig. 3 shows a schematic side view of a variant of the vibration plate from Fig. 2 .

[0082] The vibration plate also has an upper mass 1 and a lower mass 2. The ground contact plate 4, on which the vibration exciter 21 is mounted, is provided on the lower mass 2. The vibration exciter 21 not only contains the actual excitation unit but also integrates the electric motor 5.

[0083] The battery 10 and an air duct device 30 are provided on the upper mass 1.

[0084] The air guiding device 30 is a compact unit that extends vertically with a vertical component. The fan device 15 for generating the cooling air flow 16 is provided in the air guiding device 30. The cooling air flow 16 is in Fig. 3 symbolized by several arrows of different sizes, whereby the reference number 16 is not applied to each arrow in order not to impair the clarity of the image representation.

[0085] Furthermore, the converter 11 is held in the air guide device 30. The converter 11 is arranged essentially vertically and is exposed to the cooling air flow 16 on both sides.

[0086] At its lower end, the air guiding device 30 penetrates the upper mass 1 downwards so that the cooling air flow 16 can be discharged via an air outlet opening 31.

[0087] As in Fig. 3 As can be seen, the cooling air flow 16 is redirected in the direction of the vibration exciter 21 and the electric motor 5, so that it can still be used for cooling there.

[0088] The vibration exciter 21 and the electric motor 5 are mounted on the ground contact plate 4 in such a way that they can be optimally circulated by the cooling air flow 16. In particular, it can be provided that the cooling air flow 16 can also flow beneath the electric motor 5, between the electric motor 5 and the ground contact plate 4, in order to improve the cooling effect.

[0089] At the upstream end, an intake opening 32 is formed on the upper side of the upper mass 1, through which cooling air can flow from the environment. The arrangement of the intake opening 32 on the upper side allows the cooling air to enter the upper mass 1 as dust- and dirt-free as possible.

[0090] The cooling air flow 16 is subsequently passed along the walls of the battery 10 or through the battery 10.

[0091] The fan device 15 generating the cooling air flow 16 is arranged in the upper region of the air guiding device 30. Upstream of the fan device 15 and downstream of the battery 10, an air inlet opening 33 is provided through which the cooling air flow 16 can enter the air guiding device 30 after being transported by the fan device 15.

[0092] Fig. 4 shows the connection between Fig. 3 in enlarged, reduced representation.

[0093] Here, the air guiding device 30 is designed in an arc shape in order to guide the cooling air flow 16 effectively along the converter device 11.

[0094] Here, too, it can be seen how the cooling air flow 16 is divided after exiting the air guiding device 30 via the air outlet opening 31 in order to flow around the vibration exciter 21 with the electric motor 5.

Claims

1. Work machine comprising: - a work apparatus for effecting a work movement; and comprising - a drive for driving the work apparatus; wherein - the drive has an electric drive motor (5), an electric energy storage device (10) for supplying the drive motor (5) with electric current, and a converter device (11) for converting the current from the energy storage device (10) and for supplying the current to the drive motor (5); - a cooling device is provided for cooling the energy storage device (10) and the converter device (11); - the cooling apparatus has at least one fan device (15) for generating a cooling airflow (16) which can be guided via the energy storage device (10) and the converter device (11); - the fan device (15) has a fan and a fan motor which drives the fan; - the fan motor is provided separately from the drive motor (5) of the drive; - an upper mass (1) and a lower mass (2) are provided; - the lower mass (2) is movable relative to the upper mass (1); - the energy storage device (10), the converter device (11) and the cooling apparatus are arranged on the upper mass (1); - a ground contact plate (4) for carrying out the work movement is provided on the lower mass (2), characterised in that - an air-guiding device (30) is provided on the upper mass (1); - the cooling airflow (16) is guided at least partially by the air-guiding device (30); and wherein - the air-guiding device (30) supports the converter device (11).

2. Work machine as claimed in claim 1, wherein the cooling airflow (16) is guided between the energy storage device (10) and the converter device (11).

3. Work machine as claimed in any one of the preceding claims, wherein the fan is arranged in the cooling airflow (16) between the energy storage device (10) and the converter device (11).

4. Work machine as claimed in any one of the preceding claims, wherein a vibration-decoupling device is provided between the air-guiding device (30) and the remaining upper mass (1).

5. Work machine as claimed in any one of the preceding claims, wherein - the energy storage device (10) is held in a storage battery receptacle; - the storage battery receptacle and the air-guiding device (30) are coupled to one another; and wherein - the storage battery receptacle and the air-guiding device (30) are jointly fastened to the upper mass (1) in a manner which is vibration-decoupled by means of the vibration-decoupling device.

6. Work machine as claimed in any one of the preceding claims, wherein - the air-guiding device (30) has a support structure and a cover device which can be assembled together to form a unit; - the support structure is configured to support the fan device (15) and the converter device (11); and wherein - the support structure and the cover device form, in the assembled state, an air duct which extends at least between the fan device (15) and the converter device (11).

7. Work machine as claimed in any one of the preceding claims, wherein the support structure can be fastened to the upper mass (1) as a unit together with the fan device (15) and the converter device (11).

8. Work machine as claimed in any one of the preceding claims, wherein the air-guiding device (30) has an air entry opening (33) which is provided upstream of the fan device (15) and can be arranged downstream of the energy storage device (10).

9. Work machine as claimed in any one of the preceding claims, wherein the air-guiding device (30) has an air exit opening (31) which is provided downstream of the converter device (11) and is directed downwards.

10. Work machine as claimed in any one of the preceding claims, wherein an opening, through which the air-guiding device (30) extends downwards in the direction of the lower mass (2), is provided in the upper mass (1).

11. Work machine as claimed in any one of the preceding claims, wherein - the lower mass (2) has a vibration exciter (21), which is arranged on the ground contact plate (4), for generating vibrations which can be utilised by the ground contact plate (4) for the purpose of ground compaction; and wherein - the cooling airflow (16) exits via the air exit opening (31) and is guided in the direction of the vibration exciter (21) which is provided on the lower mass (2).

12. Work machine as claimed in any one of the preceding claims, wherein - the cooling apparatus has at least two fan devices (15); and wherein - the airflows generated by the two fan devices (15) can be merged to form a common cooling airflow (16).

13. Work machine as claimed in any one of the preceding claims, wherein an intake opening (32) for the cooling airflow (16) is provided upstream of the energy storage device (15) on an upper side of the upper mass (1).