Industrial truck

Abstract

The invention relates to an industrial truck (100, 101), in particular a low floor vehicle or heavy-load platform vehicle, having a frame (1) which has a loading surface (3) for receiving loads, and having at least two first wheel arrangements (2) which can each be steered about a rotational axis (D) and each have at least two drive wheels (6a, 6b) arranged on a wheel carrier (5) for driving the vehicle (100, 101) and a centrally arranged lifting device (4) for regulating the height of the wheel carrier (5) relative to the loading surface (3). The first wheel arrangement (2) has at least one electric drive (7a, 7b) for driving the drive wheels (6a, 6b).

Description

[0001] Industrial truck

[0002] The invention relates to an industrial truck, in particular a low-floor vehicle or also called a heavy-duty platform vehicle, with a frame which has a loading area defining a plane for receiving loads, and with at least two first wheel assemblies which are each rotatably mounted or steerable about a rotation axis and which each have at least two drive wheels arranged on a wheel carrier for driving the vehicle and a lifting device for adjusting the height of the wheel carrier relative to the loading area.

[0003] Such vehicles are particularly well-known in the field of heavy-duty transport. The frame typically forms a full-surface loading platform on which heavy loads, containers, or other goods can be transported. Such vehicles are often built in a modular design and can be operated in conjunction with other, similar vehicles.

[0004] Such vehicles must be particularly reliable and robust due to the special conditions they operate under, particularly the high loads caused by the heavy weight of the goods being transported. Furthermore, the goods must be transported safely and securely. Therefore, the chassis of such vehicles is of particular importance. For example, DE 10 2004 025 159 A1 describes a heavy-duty transporter for transporting heavy loads. The transporter comprises a frame with a loading platform and several wheel assemblies designed as heavy-duty chassis.

[0005] Such chassis are typically equipped with so-called hydrostatic drive systems, in which the lifting device and drive systems are operated by hydraulic pressure. However, the hydraulic lines required for this, as well as the hydrostatic drive systems themselves, add considerable additional weight to the vehicle, usually require a certain amount of space, and are sometimes complex to manufacture and assemble. Furthermore, such systems are relatively energy- and maintenance-intensive during operation, so potential weak points and leaks must be identified and prevented early on.

[0006] Today, industrial trucks with hydrostatic drives are often equipped with electric motors to drive the hydraulic pumps. The electric motor is usually located on the frame, specifically underneath the loading area. This allows the hydraulic pressure required to operate the hydrostatic drive to be generated with low emissions compared to combustion engines. However, despite such an electric motor-pump unit, the aforementioned problem of a relatively energy-inefficient system still exists. Furthermore, the interaction between the electric motor and hydraulic pump, as well as ultimately the pressure distribution in the hydraulic lines, can result in jerky starting behavior, which is generally undesirable, especially when transporting loads, and can sometimes even be dangerous.

[0007] A further disadvantage is the relatively wide wheel arrangement of such industrial trucks. Especially when the drive motor is arranged between two drive wheels of a wheel arrangement, the latter is relatively wide. Vehicles with such wheel arrangements arranged side by side therefore generally have a relatively large width. However, the demand for narrow and compact vehicles is growing, particularly in warehouse logistics. The object of the present invention is therefore to provide an industrial truck that improves at least one of the aforementioned disadvantages and, in particular, enables cost-effective production as well as low-energy and low-maintenance operation.

[0008] The invention solves the stated problem by means of an industrial truck having the features of the main claim. Advantageous embodiments and further developments of the invention are disclosed in the subclaims, the description, and the figures.

[0009] According to the invention, the first wheel arrangement has at least one electric drive for driving the drive wheels. By arranging the electric drive directly on the drive wheels as a replacement for a hydrostatic drive, both simplified and reliable control of the drive wheels is enabled. In particular, a particularly energy-efficient, space-saving, and relatively lightweight drive of the vehicle is enabled. Furthermore, by omitting the hydraulic lines for the travel drive, both the production and the maintenance intensity of the vehicle can be comparatively significantly reduced. The electric drive can, for example, be designed as an electric motor, in particular as an electric direct drive. The electric motor can, in particular, be designed as an asynchronous motor or synchronous motor. This enables a particularly energy-efficient drive compared to hydrostatic drives.

[0010] It should be clear that, for the purposes of this application, the term "loads" refers not only to goods to be transported, but also to any type of load, in particular superstructures such as manipulators, robots, lifting platforms, or other vehicle superstructures. In the latter cases, the industrial truck can serve, in particular, as a chassis.

[0011] In one embodiment of the invention, it is provided that at least two second wheel assemblies are additionally provided, which are mounted rotatably about a rotation axis and each have at least two non-driven running wheels arranged on a wheel carrier and a centrally arranged lifting device for adjusting the height of the wheel carrier relative to the loading area. In particular, the industrial truck can have both driven and non-driven wheel assemblies for driving. The structure of the wheel assemblies, in particular the lifting devices, can be identical; in particular, the non-driven wheel assemblies for driving could have the same design as the driven wheel assemblies for driving. Consequently, the wheel assemblies equipped with drive wheels can serve to move the industrial truck forward, and the wheel assemblies equipped with running wheels can serve to improve weight distribution.This means that the industrial truck has a particularly energy-efficient drive and is also suitable for particularly heavy loads.

[0012] Particularly preferably, each drive wheel of a first wheel arrangement has its own electric drive. The spaced-apart arrangement of the drive wheels of a first wheel arrangement allows the first wheel arrangement to rotate about a vertical axis when the drive wheels are set to different speeds, so that the first wheel arrangement performs a steering movement relative to the frame. This enables, in particular, continuously variable steering. In particular, this allows the industrial truck to perform individual cornering, as well as diagonal or transverse travel, making it particularly maneuverable.

[0013] The electric drive is preferably arranged at least partially radially between the wheel carrier and the drive wheel. Sectionally is understood to mean, in particular, a partial area in the axial direction of the electric motor, in particular in the axial direction of an output shaft. The electric drive can be at least partially radially surrounded by the drive wheel. In particular, the electric drive can be integrated into the drive wheel. This enables a particularly compact and space-saving arrangement of the electric drive and the entire first wheel arrangement. In particular, the first wheel arrangement can have a particularly small width overall. Thus, such a first wheel arrangement enables the design of particularly narrow industrial trucks, as are increasingly in demand in warehouse logistics.Furthermore, this allows the industrial truck to have a particularly low height and is therefore particularly suitable for loading and unloading goods from low heights. Preferably, each electric drive can be controlled separately. For this purpose, the vehicle can have a vehicle control unit which is designed to control each of the electric drives individually. This allows the first wheel arrangement to be steered relative to the frame by means of a suitable control of the electric drives of the drive wheels, in particular by controlling two drive wheels of a first wheel arrangement at different rotational speeds and / or in different rotational directions. The steering of the first wheel arrangement can thus take place in the manner of so-called tank steering. This makes the industrial truck particularly maneuverable and can perform individual cornering as well as diagonal or transverse travel.

[0014] Preferably, a vehicle control unit is provided to control the lifting device and / or the electric drive. This control unit can be operated by means of software, in particular for autonomous driving, and / or by means of a remote control from a short distance from the vehicle, in particular via a wireless connection. In particular, it can be provided that the entire vehicle is designed to be suitable for autonomous driving. The control of the electric motor can be fully automatic, in particular depending on predefined data.

[0015] The lifting device is preferably designed as a hydraulically operated lifting device, for example, as a pressure-media-operated lifting cylinder. The lifting cylinder serves to raise and lower the loading area relative to the ground. Furthermore, uneven ground can be compensated for using the lifting cylinder.

[0016] The first wheel arrangement can comprise more than two drive wheels, for example four wheels. If four drive wheels are arranged, the first wheel arrangement comprises two wheel carriers. Advantageously, the electric drives of the two drive wheels arranged one behind the other in the main direction of travel are each interconnected. It can also be provided that one of the wheels arranged one behind the other in a first wheel arrangement is designed as the drive wheel and the other as a non-driven running wheel. The running wheel serves in particular to distribute the weight over the largest possible contact surface. In this case, the main direction of travel is understood to mean in particular the direction in the longitudinal extension of the vehicle.

[0017] The industrial truck can be configured as an AGV (Automated Guided Vehicle), meaning it is self-driving. For this purpose, the truck can be equipped with a vehicle control unit that can transmit computer-based or remotely controlled control signals to the drive motors. In this case, the truck is equipped with the detection devices typically required for autonomous or automatic operation.

[0018] Preferably, the first wheel arrangements and / or the second wheel arrangements are each designed to be independently steerable. This allows the industrial truck to perform individual cornering, as well as diagonal or transverse travel, making it particularly maneuverable.

[0019] Particularly preferably, the first wheel assembly and / or the second wheel assembly are each mounted so as to be freely rotatable relative to the frame, in particular without gears, in particular without a steering drive. In this case, steering is achieved via the different control or speed of the individual drive wheels of a first wheel assembly. This allows the industrial truck to have a particularly low height and thus be particularly suitable for loading and unloading from low heights.

[0020] Preferably, the first wheel arrangement and / or the second wheel arrangement is / are steerable relative to the frame by means of a hydraulic steering drive. The hydraulic steering drive can be designed as a hydraulic steering drive known per se. Particularly preferably, the driven wheels are steered via the electric drives, in particular in the manner of a so-called tank steering system, and the running wheels are steered via the hydraulic steering drive. This allows all wheels or wheel arrangements of the industrial truck to be steerable, so that, in particular, friction or increased effort when cornering can be avoided. It can further be provided that the wheels driven by the electric drive are also steerable by means of a hydraulic steering drive.As a result, the first wheel arrangement can be hydraulically steered, for example, in the event of a defect in an electrical unit, such as an electrical control device or an electric drive motor.

[0021] In a preferred embodiment, the first wheel assembly and / or the second wheel assembly are rotatably mounted relative to the frame on a receiving area lying in the plane. This enables a particularly space-saving arrangement of the wheel carrier on the vehicle chassis.

[0022] Preferably, the first wheel assembly and / or the second wheel assembly are each designed as a steering-lifting axle, in which the rotational axis of the respective wheel assembly corresponds to the longitudinal axis of the lifting device. The lifting device is located longitudinally in the vertical central axis, the so-called force axis, of the wheel assembly. The wheel assembly can be rotatable relative to the frame about a rotational axis substantially perpendicular to the loading area, wherein the longitudinal axis of the lifting device and the rotational axis for steering the wheel assembly coincide.

[0023] In one embodiment of the invention, the wheel carrier is connected to the frame exclusively via the lifting device, in particular being mounted on the frame, in particular on a receiving area lying in the plane. This enables a particularly compact and space-saving first and / or second wheel arrangement.

[0024] Particularly preferably, the wheel carrier has two distal ends along its longitudinal extension, at each of which at least one wheel, in particular a drive wheel or a running wheel, is arranged. In particular, the wheel carrier can have a first distal end, at which a first wheel is arranged, and a second distal end opposite the first distal end, at which a second wheel is arranged.

[0025] The wheel carrier is preferably arranged longitudinally parallel to the wheel axis of the wheels, in particular in the wheel axis of at least two wheels. This enables a particularly compact and space-saving first wheel arrangement. Advantageously, the wheel carrier is designed as a wheel rocker or wheel carrier rocker for compensating for uneven ground, with at least one wheel at the distal end of the wheel carrier and with a bearing on the frame in a medial central region of the wheel carrier arranged between the drive wheels. This enables a particularly simple and compact design. Furthermore, uneven ground between one wheel and the other wheel of a first wheel arrangement can be compensated for by the pendulum-capable wheel rocker.

[0026] Preferably, the wheel carrier is mounted in an articulated manner relative to the lifting device, in particular pivotable, particularly pivotable about a pivot axis extending perpendicular to the wheel axis. This allows for particularly suitable compensation of uneven ground between the wheels of a wheel arrangement.

[0027] It is advantageously provided that the lifting device comprises a single lifting cylinder, which is arranged between the frame and the wheel carrier, in particular centrally on the wheel carrier. This enables a particularly compact and space-saving wheel arrangement.

[0028] Particularly preferably, the lifting device is positioned centrally between the wheels. This allows for particularly effective compensation of uneven ground. Furthermore, it allows for a compact and space-saving wheel arrangement.

[0029] In one embodiment of the invention, a hydraulic coupling is provided between at least two lifting devices, in particular for compensating for uneven ground. The hydraulic coupling can be provided, in particular, between the lifting devices of two wheel assemblies arranged one behind the other in the main direction of travel or between the lifting devices of two wheel assemblies arranged next to each other in the axial direction of the wheels. This allows height differences and uneven ground to be compensated for in a particularly simple and effective manner. An exemplary embodiment of the invention is explained in more detail below with reference to the figures. The same reference numerals denote the same components. The following schematically show:

[0030] Figure 1 - a perspective view of a first embodiment of an industrial truck according to the invention;

[0031] Figure 2 - a bottom plan view of the truck according to Fig.l;

[0032] Figure 3 - a side view of the industrial truck according to Fig.l;

[0033] Figure 4 - a perspective view of a first wheel arrangement of the industrial truck according to Fig.l;

[0034] Figure 5 - a side view of the first wheel arrangement according to Fig.3; and

[0035] Figure 6 - a sectional view of the first wheel arrangement according to Fig.3; and

[0036] Figure 7 - a bottom plan view of a second embodiment of an industrial truck according to the invention.

[0037] In Figures 1 to 3, a first embodiment of the industrial truck according to the invention is shown, each designated by reference numeral 100. The industrial truck 100 is designed as a low-floor vehicle, or heavy-duty platform vehicle, and in particular has a frame 1 and a plurality of first wheel assemblies 2 supporting the frame 1. In the present case, the industrial truck 100 comprises a total of eight first wheel assemblies 2, each of which is identically designed and can be controlled independently of one another. Therefore, reference is made below only to a first wheel assembly 2, which applies equally to each first wheel assembly 2.

[0038] The frame 1 comprises a chassis that is elongated in a main direction of travel F of the industrial truck 100 and has a full-surface loading area, also called a loading platform 3, on its upper side. This allows goods to be transported (not shown), for example, to be driven underneath and picked up as cargo by lifting the industrial truck 100 onto the loading platform 3. Additional units can be arranged on the frame 1 in the middle of the vehicle, as seen in the main direction of travel F. Such additional units can be provided for operating the industrial truck 100 and can include, for example, a vehicle control unit, a hydraulic pump, and / or a battery.

[0039] The first wheel assembly 2, shown in detail in Figures 4 to 6, comprises two drive wheels 6a, 6b arranged on a wheel carrier 5, which is also called a wheel cross member or wheel rocker, for driving the vehicle 100. Furthermore, the first wheel assembly 2 comprises a centrally arranged lifting device 4 for adjusting the height of the wheel carrier 5 relative to the loading area 3. The lifting device 4 is designed as a single lifting cylinder 4a. The lifting cylinder 4a is located, in particular, axially between the two drive wheels 6a, 6b.

[0040] Each first wheel assembly 2 is mounted relative to the frame 1 about a substantially vertical axis of rotation D, in particular without a gear or steering drive. The mounting is provided in particular in an upper end region of the lifting device 4 or the lifting cylinder 4a, in particular between the lifting device 4 and the frame 1, in particular in a receiving region 10. The wheel carrier 5 is arranged in a lower region of the lifting device 4 or the lifting cylinder 4a.

[0041] The wheel carrier 5 is arranged essentially horizontally in its longitudinal extension and has two distal ends 5a, 5b, at each of which at least one drive wheel 6a, 6b is arranged. As a result, the two drive wheels 6a, 6b are arranged at a distance from one another. The wheel carrier 5 has a central axis M, which coincides with the wheel axis A of the two drive wheels 6a, 6b.

[0042] The wheel carrier 5 is designed as a wheel rocker to compensate for uneven ground, with a bearing relative to the frame 1 in a medial central region 5c of the wheel carrier 5 arranged between the drive wheels. In particular, the bearing relative to the frame 1 is provided via the lifting device 4. The wheel carrier 5 is articulated relative to the lifting device 4, in particular freely pivotable about a pivot axis S, which is arranged essentially horizontally and extends perpendicular to the wheel axis A of the drive wheels 6a, 6b. This results in a type of rocker function for the wheel carrier 5. The first wheel arrangement 2 is designed in the present case as a steering-lifting axle known per se, wherein the steering-lifting axle in the present case does not have a hydrostatic drive, but rather, according to the invention, an electric drive 7a, 7b. In particular, each drive wheel 6a, 6b has an electric drive 7a, 7b.

[0043] The electric drive 7a, 7b is arranged, at least in sections, radially between the wheel carrier 5 and the drive wheel 6a, 6b. In particular, the electric drive 7a, 7b is radially surrounded by the drive wheel 6a, 6b, as shown in particular in Figure 6.

[0044] Each electric drive 7a, 7b can be controlled separately, in particular such that each first wheel assembly 2 can be steered by means of a suitable control of the electric drive 7a, 7b. The invention takes advantage of the fact that the drive wheels 6a, 6b are arranged at a distance from one another. By controlling two wheels 6a, 6b of a first wheel assembly 2 at different rotational speeds and / or in different rotational directions, rotation of the first wheel assembly 2 and thus steering relative to the frame 1 can be effected.

[0045] A controller is provided for controlling the electric drive 7a, 7b. This controller can also be provided for controlling the lifting device 4. The controller can preferably be operated by means of a remote control from a short distance from the vehicle 100, in particular via a wireless connection.

[0046] The second embodiment of an industrial truck according to the invention, shown in Figure 7 with the reference numeral 101, is essentially constructed identically to the previously shown industrial truck 100, except that all wheel assemblies have drive wheels 6a, 6b. Thus, the industrial truck 101 provides both first wheel assemblies 2 with wheel carriers 5 and driven wheels 6a, 6b and second wheel assemblies 2a with wheel carriers 11 and non-driven running wheels 8a, 8b. The non-driven running wheels 8a, 8b serve in particular for weight distribution. The first wheel assemblies 2 are essentially constructed identically to the second wheel assemblies 2a, except that non-driven running wheels 8a, 8b without a drive motor are provided on the wheel carrier 11. The running wheels 8a, 8b can in particular be free-running wheels. Consequently, the wheel carriers 11 are constructed essentially the same as the wheel carriers 5, except that a drive motor is not provided in the wheel carrier 11.In particular, the lifting device 4 can be constructed and arranged in the same way for both wheel carriers 5, 11 or wheel arrangements 2, 2a.

[0047] The steering or rotation of the second wheel arrangement 2a about the rotation axis D is not carried out - as in the case of the wheel arrangement 2 - by means of a so-called "tank steering" of the electrically driven drive wheels 6a, 6b, but by means of a hydraulic steering drive 9 known per se.

[0048] Reference list:

[0049] 1 frame

[0050] 2 first wheel arrangement

[0051] 2a second wheel arrangement

[0052] 3 loading area

[0053] 4 Lifting device

[0054] 4a Lifting cylinder

[0055] 5 wheel carriers

[0056] 5a distal end

[0057] 5b distal end

[0058] 5c Midrange

[0059] 6a Drive wheel

[0060] 6b Drive wheel

[0061] 7a electric drive

[0062] 7b electric drive

[0063] 8a wheel

[0064] 8 b wheel

[0065] 9 hydraulic steering drive

[0066] 10 Recording area

[0067] 11 wheel carriers

[0068] 100 industrial trucks

[0069] 101 Industrial truck

[0070] A wheel axle

[0071] D axis of rotation

[0072] L Longitudinal axis

[0073] S swivel axis

[0074] F Main direction of travel

[0075] M central axis

Claims

Patent claims:

1. Industrial truck (100, 101), in particular a low-floor vehicle or heavy-duty platform vehicle, with a frame (1) which has a loading surface (3) defining a plane (E) for receiving loads, and with at least two first wheel assemblies (2) which are each rotatably mounted about a rotation axis (D), each having at least two drive wheels (6a, 6b) arranged on a wheel carrier (5) for driving the vehicle (100, 101) and a centrally arranged lifting device (4) for adjusting the height of the wheel carrier (5) relative to the loading surface (3), characterized in that the first wheel arrangement (2) has at least one electric drive (7a, 7b) for driving the drive wheels (6a, 6b).

2. Industrial truck (100, 101) according to claim 1, characterized in that at least two second wheel assemblies (2a) are additionally provided, which are mounted rotatably about an axis of rotation (D), each of which has at least two non-driven running wheels (8a, 8b) arranged on a wheel carrier (11) and a centrally arranged lifting device (4) for adjusting the height of the wheel carrier (11) relative to the loading area (3).

3. Industrial truck (100, 101) according to one of claims 1 or 2, characterized in that each drive wheel (6a, 6b) has an electric drive (7a, 7b).

4. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the electric drive (7a, 7b) is arranged at least in sections radially between the wheel carrier (5) and the drive wheel (6a, 6b).

5. Industrial truck (100, 101) according to one of the preceding claims, characterized in that each electric drive (7a, 7b) can be controlled separately, in particular in such a way that each first wheel arrangement (2) can be steered by means of a suitable control of the electric drive (7a, 7b). bar, in particular by controlling two wheels (6a, 6b) of a first wheel arrangement (2) with different rotational speeds and / or in different directions of rotation.

6. Industrial truck (100, 101) according to one of the preceding claims, characterized in that a control is provided for controlling the lifting device (4) and / or the electric drive (7a, 7b), which control can be operated by means of software, in particular for autonomous driving, and / or by means of remote control from a close range of the vehicle (100, 101), in particular via a wireless connection.

7. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the first wheel arrangements (2) and / or the second wheel arrangements (2a) are each designed to be steerable independently of one another.

8. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the first wheel arrangement (2) and / or the second wheel arrangement (2a) is mounted so as to be freely rotatable relative to the frame (1), in particular without a gear, in particular without a steering drive.

9. Industrial truck (100, 101) according to one of claims 1 to 7, characterized in that the first wheel arrangement (2) and / or the second wheel arrangement (2a) can be steered relative to the frame (1) by means of a hydraulic steering drive (9).

10. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the first wheel arrangement (2) and / or the second wheel arrangement (2a) is rotatably mounted relative to the frame (1) on a receiving area (10) lying in the plane (E).

11. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the first wheel arrangement (2) and / or the second wheel arrangement (2a) is designed as a steering-lifting axle, in which the axis of rotation (D) of the respective wheel arrangement (2, 2a) corresponds to the longitudinal axis (L) of the lifting device (4).

12. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the wheel carrier (5, 11) is connected to the frame (1) exclusively via the lifting device (4), in particular is mounted on the frame (1), in particular on a receiving area (10) lying in the plane (E).

13. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the wheel carrier (5, 11) has two distal ends (5a, 5b) in its longitudinal extent, at each of which at least one wheel, in particular a drive wheel (6a, 6b) or a running wheel (8a, 8b), is arranged.

14. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the wheel carrier (5, 11) is arranged in the longitudinal extension parallel to the wheel axis (A) of the wheels (6a, 6b, 8a, 8b), in particular coinciding with the wheel axis (A) of at least two wheels (6a, 6b, 8a, 8b).

15. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the wheel carrier (5, 11) is designed as a wheel rocker for compensating for uneven ground, with at least one wheel (6a, 6b, 8a, 8b) at a distal end (5a, 5b) of the wheel carrier (5, 11) and with a bearing on the frame (1) in a medial central region (5c) of the wheel carrier (5, 11).

16. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the wheel carrier (5, 11) is mounted in an articulated manner relative to the lifting device (4), in particular freely pivotable, in particular pivotable about a pivot axis (S) which extends perpendicular to the wheel axis (A) of the wheels (6a, 6b, 8a, 8b).

17. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the lifting device (4) has a (single) lifting cylinder (4a) which is arranged between the frame (1) and the wheel carrier (5, 11), in particular centrally on the wheel carrier (5, 11).

18. Industrial truck (100, 101) according to one of the preceding claims, characterized in that the lifting device (4) is arranged between the wheels (6a, 6b, 8a, 8b).

19. Industrial truck (100, 101) according to one of the preceding claims, characterized in that a hydraulic coupling is provided between at least two lifting devices (4), in particular for compensating for uneven ground.

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