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 A1 discloses a soil compaction device with an air-cooled battery. The battery is attached to a guide handle of the soil compaction device. An air conveyor device is provided for generating a cooling air flow for the battery. The air conveyor device is driven by a drive motor of the soil compaction device.

[0007] The invention is based on the object of providing a working 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] 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.

[0037] 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.

[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 a schematic side sectional view of a working machine according to the invention as a vibratory rammer; and Fig. 2 in schematic side view another working machine according to the invention as a vibrating plate.

[0039] 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.

[0040] 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.

[0041] To supply energy to the electric motor 5, a battery 10 serving as an electrical energy storage device is provided.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] To better guide the cooling air flow 16 and to protect the various components, a cover 17, e.g. a plastic hood, is provided.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The battery 10, which provides the energy for the electric motor 5, is arranged on the upper mass 1, together with the converter 11.

[0054] As with the embodiment of Fig. 1The 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.

[0055] The cover 17 is provided to improve the guidance of the cooling air flow 16.

[0056] 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.

Claims

1. Work machine comprising: - a work device for effecting a work movement; and comprising - a drive for driving the work device, wherein - the drive has an electric drive motor (5), an electric energy storage device (10) for supplying the drive motor (5) with an 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 apparatus 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, characterised in that - the fan motor is provided separately from the drive motor (5) of the drive; and wherein - the fan is arranged in the cooling airflow (16) between the energy storage device (10) and 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 a fan control device is provided for activating the fan motor.

4. Work machine as claimed in any one of the preceding claims, wherein - 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); and wherein - a ground contact plate (4) for carrying out the work movement is provided on the lower mass (2).

5. Work machine as claimed in any one of the preceding claims, wherein - the upper mass (1) has a handle device (13) for guiding the work machine by a user; and wherein - the energy storage device (10) and the fan device (15) are arranged on the handle device (13).

6. Work machine as claimed in any one of the preceding claims, wherein the converter device (11) is arranged on the handle device (13).

7. Work machine as claimed in any one of the preceding claims, wherein - a cover (17) is provided on the handle device (13); and wherein - the energy storage device (10) and / or the fan device (15) and / or the converter device (11) are arranged under the cover (17).

8. Work machine as claimed in any one of the preceding claims, wherein the work machine is a ground compaction apparatus.