Drive unit for an industrial truck

Abstract

The invention relates to a drive unit for an industrial truck, with a steerable running wheel (1) which is attached to a vehicle frame so as to be pivotable about a vertical pivot axis, wherein a drive motor 14, 14' with a drive shaft 13, 13' is arranged coaxially to the pivot axis, which in turn is drivingly connected to the running wheel 1 via a gearing. With a releasable parking brake 10, 10' acting on the drive shaft 13, 13'. A brake shaft 9, 9' of the parking brake 10, 10' can be rotatably driven by the drive shaft 13, 13' of the drive motor 14, 14' via an auxiliary gearing 12, 12' which reduces the speed of the drive shaft 13, 13' of the drive motor, from which brake shaft 9, 9' the running wheel 1 can in turn be rotatably driven via the gearing.

Description

[0001] The invention relates to a drive unit for an industrial truck, with a steerable running wheel which is pivotally mounted on a vehicle frame about a vertical pivot axis, wherein a drive motor with a drive shaft is arranged coaxially to the pivot axis, which in turn is drive-connected to the running wheel via a gear, and with a releasable parking brake acting on the drive shaft.

[0002] In such a drive unit, it is known that the parking brake can be used to brake the drive shaft of the drive motor. The drive motor can accelerate or decelerate the vehicle. Since the size of the drive motor, particularly when designed as an electric machine, depends essentially on the torque of the drive motor, it is advantageous to aim for the highest possible speed for the drive motor and, in return, a lower torque for the drive motor. However, conventional parking brakes cannot be operated at any desired high speed. The size of the parking brake depends on the required braking torque and the maximum kinetic energy of the vehicle. In the event of an emergency braking using the parking brake, it should be able to dissipate the entire kinetic energy of the vehicle without becoming excessively hot.

[0003] The object of the invention is to provide a drive unit for an industrial truck of the type mentioned at the outset, which avoids these disadvantages, has a simple structure of small size and enables the use of a drive motor with the highest possible speed if the parking brake is not overloaded.

[0004] This object is achieved according to the invention in that a brake shaft of the parking brake can be rotatably driven by the drive shaft of the drive motor via an auxiliary gear that reduces the speed of the drive shaft of the drive motor, from which brake shaft the impeller can in turn be rotatably driven via the gear.

[0005] This design allows the drive motors, which are preferably electric motors, to have high speeds of, for example, between 7,000 and 15,000 rpm while being smaller and more cost-effective. The auxiliary gear reduces the speed of the drive motor's drive shaft and increases the torque accordingly.

[0006] During braking, when the parking brake is used as an emergency brake, the power flow is reversed.

[0007] If the drive motor and / or the auxiliary gearbox and / or the parking brake are designed as modules that can be assembled, this module can be easily replaced if one of these modules is defective.

[0008] A small installation space requirement is achieved if the drive shaft of the drive motor and the brake shaft of the parking brake are arranged coaxially to each other.

[0009] The auxiliary gearbox can be located either below the drive motor and the parking brake below the auxiliary gearbox or above the drive motor and the parking brake above the auxiliary gearbox.

[0010] If the auxiliary gearbox is located above the drive motor and the parking brake above the auxiliary gearbox, the drive motor's drive shaft can be designed as a hollow shaft to save space, through which the parking brake brake shaft is routed to the gearbox. Furthermore, the parking brake is easily accessible for servicing.

[0011] If the auxiliary gear is a single-stage planetary gear, this has the advantage of saving space because the input and output of the auxiliary gear are arranged coaxially to each other.

[0012] If the gearbox is a brake shaft speed reducing gearbox, the speed is further reduced and the torque is increased to drive the impeller.

[0013] The transmission can be any suitable drive transmission such as a gear, friction wheel or traction transmission or a combination thereof.

[0014] To save space, the gearbox can be a spur gear-bevel gear or a spur gear-planetary gear.

[0015] Embodiments of the invention are illustrated in the drawings and described in more detail below. They show: Fig. 1 a perspective view of a first embodiment of a drive unit Fig. 2 a longitudinal section of the drive unit according to Fig. 1 Fig. 3 an enlarged partial longitudinal section after Fig. 2 Fig. 4 a perspective view of a second embodiment of a drive unit Fig. 5 a longitudinal section of the drive unit according to Fig. 4 Fig. 6 an enlarged partial longitudinal section after Fig. 5.

[0016] The drive units for an industrial truck shown in the figures have a wheel 1 that is non-rotatably mounted on a horizontal wheel axle 2. The wheel axle 2 is rotatably driven by a spur-bevel gear 3.

[0017] For this purpose, a first spur gear 5 is arranged at the upper end of a vertically arranged gear shaft 4, and a bevel pinion 6 is arranged at the lower end in a rotationally fixed manner. The bevel pinion 6 engages a bevel gear 7, which is arranged in a rotationally fixed manner on the impeller axle 2.

[0018] The first spur gear 5 is rotatably driven by a second spur gear 8, which is arranged in a rotationally fixed manner on the lower end of a vertical brake shaft 9.

[0019] The brake shaft 9 is part of a parking brake 10 designed as an electrically releasable spring-loaded brake with a brake rotor 11 fixedly mounted on the brake shaft 9, which can also be used as an emergency brake in an emergency. During normal driving, the parking brake is released and only brakes when the vehicle is stationary.

[0020] The above-described components are arranged in a housing 15 in which the wheel axle 2 is also rotatably mounted and which is fastened to a frame plate 16 of a vehicle frame 16 of the industrial truck.

[0021] The housing 15 has at its upper end a steering spur gear 17 coaxial with the brake shaft 9, 9', into which a steering pinion (not shown) of a steering drive 18 arranged on the frame plate 16 engages. This allows the housing 15 and, with it, the wheel to be pivoted about a vertical axis for steering the industrial truck.

[0022] In the embodiment of the Fig. 1 to 3, the upper end of the brake shaft 9 can be driven rotatably via the output of an auxiliary gear 12 designed as a planetary gear, wherein the auxiliary gear 12 is arranged coaxially above the parking brake 10.

[0023] On the input side, the auxiliary gear 12 can be driven in rotation by the rotor shaft 13, which is coaxial with the brake shaft 9, of a drive motor 14 designed as an electric machine and arranged above the auxiliary gear 12.

[0024] In the embodiment of the Fig. 4 to 6, from bottom to top, there is first a drive motor 14', then an auxiliary gear 12' designed as a planetary gear and at the top a parking brake 10'.

[0025] The drive motor 14', the auxiliary gear 12' and the parking brake 10' largely correspond in structure to the corresponding components of the embodiment of the Fig. 1 to 3.

[0026] The only difference is that the rotor shaft 13' of the drive motor 14' is designed as a hollow shaft through which the brake shaft 9' is guided downwards and carries the second spur gear 8 at its lower end.

[0027] In both embodiments, the drive motor 14, 14', the auxiliary gear 12, 12' and the parking brake 10, 10' are designed as modules that can be assembled.

[0028] If the industrial truck is to be driven, a torque and speed can be provided by the drive motor 14, 14' on the rotor shaft 13, 13'. The rotor shaft 13, 13' drives the auxiliary gear 12, 12', which reduces the speed and increases the torque accordingly. In the examples, the auxiliary gear 12, 12' is designed as a single-stage planetary gear. This has the advantage that the input and output of the auxiliary gear 12, 12' are coaxial with one another. The output of the auxiliary gear 12, 12' drives the brake shaft 9, 9', which in turn drives the spur-bevel gear 3. The spur-bevel gear 3 further reduces the speed and increases the torque to drive the impeller 1. During service braking, the power flow is reversed.

[0029] The brake shaft 9, 9' is non-rotatably connected to the brake rotor 11 of the parking brake 10, 10', which is designed as an electrically releasable spring-loaded brake. The brake shaft 9, 9' and the brake rotor 11 have a lower speed than the drive motor 14, 14'. The speed ratio depends on the gear ratio of the auxiliary gear 12, 12'. The gear ratio of the auxiliary gear 12, 12' can be selected such that the permissible maximum speed of the brake rotor 11 is not exceeded under any operating condition, while the drive motor 14, 14' can still be operated at a high speed. The size and thus the cost of a drive motor 14, 14' depend significantly on the required torque. A high speed of the drive motor 14, 14' enables a smaller size because the required torque is lower for the same power than at a low speed.The electric parking brake 10, 10' is released both when the industrial truck is being driven and during service braking. This means that the parking brake 10, 10' does not apply any braking torque to the brake shaft 9, 9'.

[0030] The parking brake 10, 10' is normally closed (i.e. not released) when the industrial truck is stationary and needs to be held in place (parking brake function). The parking brake 10, 10' can then introduce a braking torque into the drive unit at the brake rotor 11 via the brake shaft 9, 9', thus preventing the industrial truck from moving, e.g., by rolling on an inclined surface. Since the speed of the industrial truck is zero in this operating state, the brake rotor 11 has a speed of zero. Therefore, no power is converted into the parking brake 10, 10'. Typically (e.g., according to ISO 6292), the industrial truck should be able to be held on an inclined surface with a gradient of at least 15%.

[0031] In addition, the parking brake 10, 10' can be applied while the industrial truck is moving, e.g. by actuating an emergency stop switch on the industrial truck. This initiates an emergency braking process. The kinetic energy of the industrial truck is transferred from the impeller 1 in the form of torque and speed to the spur-bevel gear 3. There, the torque and speed are converted and transferred to the brake shaft 9, 9' and the brake rotor 11 of the parking brake 10, 10'. The parking brake 10, 10' converts the torque and speed into heat during the emergency braking process and releases this heat to the environment. Since the emergency braking process only takes a short time, the parking brake 10, 10' must be able to absorb almost the entire kinetic energy of the industrial truck as heat, since it can only release a large portion of the heat to the environment after the braking process. Reference symbol 1 wheel 2 wheel axle 3 spur-bevel gears 4 Gear shaft 5 first spur gear 6 bevel pinions 7 Bevel gear 8 second spur gear 9 Brake shaft 9' brake shaft 10 Parking brake 10' parking brake 11 Brake rotor 12 auxiliary gears 12' auxiliary gearbox 13 Rotor shaft 13' rotor shaft 14 Drive motor 14' drive motor 15 housings 16 frame plate 17 Steering spur gear 18 Steering drive

Claims

[1] Drive unit for an industrial truck, with a steerable running wheel (1) which is pivotally mounted on a vehicle frame about a vertical pivot axis, wherein a drive motor (14, 14') with a drive shaft (13, 13') is arranged coaxially to the pivot axis, which in turn is drive-connected to the running wheel (1) via a gear, and with a releasable parking brake (10, 10') acting on the drive shaft (13, 13'), characterized by that a brake shaft (9, 9') of the parking brake (10, 10') can be rotatably driven by the drive shaft (13, 13') of the drive motor (14, 14') via an auxiliary gear (12, 12') which reduces the speed of the drive shaft (13, 13') of the drive motor, from which brake shaft (9, 9') the impeller (1) can in turn be rotatably driven via the gear. [2] Drive unit according to claim 1, characterized by that the drive motor (14, 14') and / or the auxiliary gear (12, 12') and / or the parking brake (10, 10') are designed as assemblable modules. [3] Drive unit according to one of the preceding claims, characterized by that the drive shaft (13, 13') of the drive motor (14, 14') and the brake shaft (9, 9') of the parking brake (10, 10') are arranged coaxially to one another. [4] Drive unit according to one of the preceding claims, characterized by that the auxiliary gear (12) is arranged below the drive motor (14) and the parking brake (10) is arranged below the auxiliary gear (12). [5] Drive unit according to one of claims 1 and 2, characterized by that the auxiliary gear (12') is arranged above the drive motor (14') and the parking brake (10') is arranged above the auxiliary gear (12'). [6] Drive unit according to claim 5, characterized by that the drive shaft of the drive motor (14') is designed as a hollow shaft through which the brake shaft (9') of the parking brake (10') is guided to the gearbox (3). [7] Drive unit according to one of the preceding claims, characterized bythat the auxiliary gear (12, 12') is a single-stage planetary gear. [8] Drive unit according to one of the preceding claims, characterized by that the gear (3) is a gear that reduces the speed of the brake shaft (9, 9'). [9] Drive unit according to one of the preceding claims, characterized by that the parking brake (10, 10') is an electrically released spring-loaded brake. [10] Drive unit according to one of the preceding claims, characterized by that the gearbox is a spur-bevel gear gearbox (3).

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