GB2401591A

GB2401591A - Fork lift vehicle with removable energy module

Info

Publication number: GB2401591A
Application number: GB0410613A
Authority: GB
Inventors: Ernst-Peter Magens
Original assignee: Jungheinrich AG
Current assignee: Jungheinrich AG
Priority date: 2003-05-15
Filing date: 2004-05-12
Publication date: 2004-11-17
Anticipated expiration: 2024-05-12
Also published as: ITTO20040310A1; GB0410613D0; DE10321773A1; GB2401591B

Description

2401 591 Counter Weight Forklift The invention relates to a counterweight

forklift as described in claim 1 of this patent.

In the material flow of palletized goods, the free-moving forklift, or counterweight forklift, is a universally used device. Counterweight forklifts are usually equipped with an internal combustion or batterypowered electrical drive motor. Depending on the type of tire used, the device may be used outside on uneven ground. Within enclosed spaces, forklifts with internal combustion engines are used only for short periods. Instead, forklifts with battery-powered electrical drive motors are used. It is also known to design the drive motor in such a way that it may be used outside or inside a closed space. An internal combustion engine drives an electrical generator, which is able to charge a battery. Using this battery, the electrical drive motor is then powered in closed spaces. During use outside the enclosed space, the internal combustion engine can be engaged, and used to drive the electrical drive motor directly over the generator.

While their basic function, that is, picking up loads outside the wheel base, and the transportation and stacking of loads, is identical regardless of the type of drive for both types of vehicle, the construction of the vehicles is quite different. Only the lift mast and the rear drive axis, as well as some control elements, are identical. The low number of identical parts hinders the use of economic advantages in the manufacture of these vehicles which would result from an increase in number for individual components if these were able to be used in both internal-combustion and battery- powered electrically driven counterweight forklifts.

Due to the differences with regards to energy storage (battery versus fuel tank) and the conversion of the stored energy (internal combustion engine versus electric motor), the state of art has resulted in typical designs for the individual components of these vehicles. One significant component is the vehicle frame. While the frame of the battery-powered electrically driven forklift is characterized by a large empty space for the battery which is nearly the entire width of the vehicle, the frame of the internal combustion driven forklift is characterized by the tanks running the length of the side, which serve as a load-bearing part of the frame. It also has a space in the middle for the drive train (intemal- combustion engine, gearbox, drive axis) which extends into the front end of the vehicle.

These and other differences in other assemblies in the vehicle have in the past resulted in the fact that these vehicles, identical in function, are very different in construction.

The battery exchanges necessary in battery-powered electrically driven forklifts used over multiple shifts are greatly hindered by the standard vehicle frame construction, while the tanks on the sides of intemalcombustion-driven forklifts greatly restrict access to the drive train during maintenance and repair work.

The current invention demonstrates a counterweight forklift which can be constructed nearly identically regardless of drive type.

In a forklift according to the invention, the frame of the vehicle underneath the driver's seat is portal-formed with an open space extending down and to the side, between the load axle and the drive axle. On the opposite sides of the open space, there are interfaces for the installation of an energy module. The energy module is laid out in such a way that it supplies electrical or hydraulic power, where at least one drive motor is coupled to the load axle with the driveshaft of the driven wheel. The drive motor is connected to the energy module by an electric or hydraulic line.

In the counterweight forklift according to the invention, there is at least one drive motor, implemented as an electric or hydraulic motor. It is to be understood that if there are two driven wheels on the load axle, each driven wheel may be assigned a drive motor. The power supply is led to the drive motor by a line which is either an electric or a hydraulic line. The energy module is thus designed so that it can supply power in either electrical or hydraulic form. Different configurations can be imagined for the energy module. The energy module could, for example, contain a battery which supplies the drive motor over electric lines. It is to be understood that the battery must be charged from time to time. If uninterrupted operation of the forklift is desired, the discharged battery must be replaced with a fully charged one and the empty unloaded in a different place. It is, however, also a possibility to include an internal combustion engine which would use a generator to drive the electric drive motor or charge a storage battery in the energy module. In this case, too, the energy module would deliver power in the form of electrical energy. Finally, it is also possible to install a fuel cell, with fuel tank and appropriate battery, to drive an electric drive motor. If hydraulic energy is desired, it is preferable to install an internal combustion engine in the energy module, which then drives one or more hydraulic pumps. The drive motor is then implemented as a hydraulic motor, for instance, as an axial or radial piston drive. It would also be possible to use a battery and an electric motor to drive a hydraulic pump, if the drive motor is a hydraulic motor.

The counterweight forklift of the invention is independently designed, regardless of which energy module is installed. The manufacture of forklifts with different drive types would thus be possible with significant savings. In the manufacture of the - 4 energy module it would only be necessary to ensure that it fits within the open space in the vehicle frame, and that it fits the interfaces in the open space. A carrying frame or carrying body is provided for the energy module. This could, if necessary, also be designed and dimensioned in a unified manner to fit to the interfaces.

The construction of such a forklift would have the further advantage that the energy module or battery could be easily installed or removed, simply by sliding it out of the side of the vehicle. This results in optimal access.

Counterweight forklifts usually comprise a so-called overhead guard, which is supported by two side beams. In the embodiment of the invention, the support of the overhead guard is used for the transmission of mechanical force from the fork to the counterweight. Thus one embodiment of the invention specifies that the force transmission proceeds on the one hand over the inverted U-shaped side beams for the overhead guard, and on the other hand over a frame section which appears from the side as a reversed Z-shape whose upper rear horizontal segment is connected to the rear support segments of the side beams, and is bounded to the front and overhead by the vertical segment of the frame part of the open space. The lower horizontal front segment of the frame part is connected to the lift mast, the load axle, and the front side beams. The side beams and the frame part constitute a closed frame over which all forces exerted by load-bearing members can be effectively transmitted. As is usual for a counterweight forklift, the load forces and moments exerted by the load are effectively balanced by the vehicle's own weight, the counterweight, and the carrying forces of the wheels. Besides the static forces and moments, dynamic forces due to driving and lifting are also taken into account.

It is of course to be understood that the vehicle frame, besides the interfaces described, also has further interfaces for vehicles components, energy storage, control elements, and drives. The energy module is naturally designed to supply further drives, particularly the lifting and steering drives, with power. If hydraulic energy is to be supplied, it can be directly led to a hydraulic drive for the load-bearing equipment. In the case of electrical energy, a conversion into hydraulic energy for the lifting and lowering drive would be required.

In the counterweight forklifts described, it is usual to include a socalled driver's seat module, which is mounted elastically on the vehicle frame. In the invention, such a driver's seat module, with driver's seat, steering wheel, control panel, and floor plate with control pedals, is also included, which is preferentially located between the lengthwise beams of the reverse Z-shaped frame section. The driver's seat module can be built identically regardless of drive type.

There are consequently only three identical assemblies to be implemented in the invented counterweight forklift, to solve the object of the invention, which is to create a counterweight forklift substantially identical regardless of drive type.

Below, one embodiment of the invention will be described in more detail.

FIG 1 shows a schematic side view of a counterweight forklift in accordance with the invention.

FIG 2 shows a top view of the counterweight forklift in FIG 1. - 6

FIG 3 shows a side view of a frame section of the counterweight forklift in FIGS 1 and2.

FIG 4 shows a side view of another assembly of the vehicle frame in FIGS 1 and 2.

FIG 5 shows a schematic side view of a driver's seat module.

The floor conveyor shown in FIGS l and 2 is a so-called counterweight forklift. It consists basically of a frame 10, which is connected to lift mast 12 on the front end, with a front load axle 3 and a rear swinging steering axle 4. In an example embodiment, load axle 3 and steering axle 4 each have two wheels 14, 16. In a three- wheeled variant, the rear steering axle is replaced with a centrally located, steerable single or double wheel. On the lift mast 12, there is a fork carrier 18 with a load fork which is adjustable in height. It is driven by a lift cylinder, not shown. The tilt of the lift mast 12 can be adjusted relative to the vehicle frame 10 using one or more tilt cylinders 22.

The vehicle frame 10 has two parallel inverted U-shaped side beams 24 on the sides, with an upper horizontal carrying segment 26 and nearly vertical support segments 28, leading downwards. The rear support segment 28 is connected to the steering axle 4 as well as to a tail weight 30a. On the front side of the steering axle 4 there is an interface 32. The front support segment 30 is connected to a drive module 34. The drive module 34 supports the lift mast 12 by means of a lower bearing, not shown, as well as the tilt cylinders 22. The load axle 3 and an interface 38 are also integrated - 7 into it. The load axle can be constructed as a continuous axle or, as in the figure, be equipped with two drive motors 40, 42.

A driver's seat 44, a steering wheel with control panel 46, and a floor plate 48 with control pedals, make up a so-called driver's seat module, as shown in FIG 5. It is elastically suspended on the drive module 34.

As shown in FIG 2, the side supports 24 are connected to one another over a front cross beam 50 and a rear cross beam 52. Parallel lengthwise beams 54 are connected with cross beams 53, which are also connected to the side supports 24. They make up the actual overhead guard.

The drive module 34, with a vertical segment 60 and an upper horizontal segment 62, makes up a reversed Z-shaped frame section. As shown in FIG 3, the frame part 66, together with the load fork 20, looks something like a cake server with wheels. This frame section 66, together with the lower segment of the support segment 28 of the side beams 24, makes up an open space 70, which serves to house an energy module, not shown. Depending on the drive type of the counterweight forklift, this open space may contain: - a battery for driving and lifting functions - a module consisting of an internal combustion engine, a generator, and an optional storage battery, along with a corresponding control - a fuel cell with fuel tank, storage battery, and further required equipment, or - 8 - an internal combustion engine with hydraulic pumps and all necessary equipment.

In the first three cases, interface 38 is supplied with electrical energy to drive the vehicle, which is carried over cables to, for example, the drive motors 40, 42. In the case of hydraulic pumps, hydraulic energy is supplied, which is carried over hydraulic lines to the drive motors 40, 42. In the latter case, the drive motors 40, 42 are then implemented as hydraulic motors, for instance, as axial or radial piston drive motors.

The supply of additional hydraulic consumers, such as lifting cylinders for the lift mast 12, steering drive, and so on, are not covered here for ease of presentation.

The design of interfaces 32, 38 and the layout of the open space 70 for the described modules makes a very simple battery or module exchange or removal possible. The battery or modules can, for example, be pulled sideways out of the vehicle for maintenance, so that optimal access is provided.

The basic construction of the vehicle according to FIGS 1 and 2, with the determining forces, is shown in FIGS 3 and 4. In these figures, the vehicle is shown in three assemblies, of which the first assembly consists of the drive module 34 with the lift mast 12 and the load axle 3, along with the frame segments 60 and 62. The second consists of the support structure for the overhead guard, along with connected parts.

The third group includes the driver's seat module as shown in FIG 5.

The triggering force is a weight 72 which is exerted on the load fork 20 by a load, not shown, on the fork. The opposing forces are the wheel load 74 on the front axle 3, and a bearing force 76 on the end of the frame segment 62 at the anchorage points 78. - 9 -

Superposed horizontal forces make up the force pair 80, 82. At the anchorage points 84, additional forces 96, 96a are transmitted from the side beams 24 into the drive module 34, and at interface 38 to the energy module, mostly vertical forces 86 and optional horizontal forces 100 from the energy module suspended there (not shown).

Depending on the type of design of interfaces 32, 38, horizontal forces may also be transmitted there, if the suspended energy module is designed accordingly. This would reduce the horizontal forces 82, 82a. 82, 82a are the inner forces, which are reduced owing to forces 98,100. The outer forces 80 are not influenced. Over points 78 and 84, drive modul 34 including frame section 66 is connected to the side beams 24. It should be mentioned that frame segment 62, as can be seen in FIG 2, consists of two lengthwise beams 66a, 66b, which are arranged parallel at a distance from one another.

The side beams 24 together with the cross beams 50, 52, and additional cross beams 53, together with the lengthwise beams 54, make up the loadbearing elements of the second assembly, which also includes the rear steering axle 4, the tail weight 30a, and the second interface 32 for support of the energy module, not shown. The forces transmitted into this assembly consist on the one hand of the interface forces from the anchorage points 78, 84 to drive modul 34 and on the other hand of forces 88 caused by the tail weight 30a, forces 90 and optionally 98, which the energy module transmits into the assembly over interface 32. The resulting force then leads to wheel force 92 on the rear steering axle 4. Additional horizontal forces are taken into account by the force arrow 94, which as an example is exerted on the rear wheels. The horizontal forces can be divided into external forces, which arise from drive resistance and from 10 dynamic loads from acceleration and braking in the horizontal direction or collision with obstacles, and internal forces, which can also result from vertical forces. The static vertical forces are also supplemented by dynamic forces during use of the forklift.

The described vehicle design results in a number of advantages: unified vehicle frame for counterweight forklifts regardless of drive type improvement of cost efficiency in production of vehicles due to high portion of identical parts improvement of cost efficiency during use of vehicle due to extremely simple battery exchange very good access to drive group/energy module during production of vehicle and also in case of service and repair exchangeability of drive groups/energy modules via defined, identical interfaces identical interfaces in the drive section to electric and hydrostatic drives identical driver's seat module for all forklifts. : - 11

Claims

Claims: 1. Counterweight forklift with a vehicle frame comprising a front

load axle with at least one driven wheel, a rear steering axle with at least one steered wheel, an overhead guard, a driver's seat, and a counterweight on the rear end, with a lift mast attached to the front end of the vehicle frame in which a load carrier can be moved up or down using a lifting drive, with a drive on the vehicle frame which drives a wheel on the load axle, characterized in that the vehicle frame (10) underneath the driver's seat (44) forms an portal-formed open space (70) extending down and to the side between the load and steering axles (3, 4), with an interface (38, 32) provided on the opposite vertical sides of the open space (70) for the installation of an energy module, the energy module being designed in such a way that it provides electrical or hydraulic power, and wherein at least one drive motor (40, 42) is coupled to the load axle (3) with the drive shaft of the driven wheel, and wherein the drive motor (40, 42) is connected with an electric or hydraulic line to the energy module.
2. Counterweight forklift according to claim 1, characterized in that the force transmission from the loadbearing member (20) and the load axle (3) to the steering axle (4) or the counterweight (30a) is performed, on the one hand, by the inverted U shaped parallel side beams (24) for the overhead guard, and on the other hand, by a frame section (66) which appears from the side as a reversed Z shape, whose upper rear horizontal section is connected to the rear support segments (28) of the side beams (24) and which bounds the open space (70) to the front and overhead along 1 1 - 12 with the vertical segment (60) of the frame section (66), and whose lower horizontal front segment is connected to the lift mast (12), the load axle (3), and the front side beams (30).
Counterweight forklift according to claim 2, characterized in that the side beams (24) are connected over an upper rear (52) and upper front cross beam (50).
4. Counterweight forklift according to claim 2 or 3, characterized in that the upper horizontal segment (62) of the reversed Z-shaped frame section (66) has parallel lengthwise beams (66a, 66b) on both sides.
5. Counterweight forklift according to claims 1 through 4, characterized in that a driver's seat module with driver's seat (44), steering wheel and control panel (46) and floor plate (48) with control pedals is elastically mounted on the vehicle frame (lo).
6. Counterweight forklift according to claims 4 and 5, characterized in that the driver's seat module is located between the lengthwise beams (66a, 66b).
7. Counterweight forklift according to claims 1 through 6, characterized in that the energy module comprises a battery and the drive motor (40, 42) is an electric motor. - 13
8. Counterweight forklift according to claims 1 through 6, characterized in that the energy module comprises an internal combustion engine and an electric generator and the drive motor (40, 42) is an electric motor.
9. Counterweight forklift according to claims 1 through 6, characterized in that the energy module comprises an internal combustion engine, an electric generator, and a storage battery, and the drive motor (40, 42) is an electric motor.
10. Counterweight forklift according to claims 1 through 6, characterized in that the energy module includes a fuel cell with fuel tank and a storage battery, and the drive motor (40, 42) is an electric motor.

Counterweight forklift according to claims 1 through 6, characterized in that the energy module includes an internal combustion engine and at least one hydraulic pump, and the drive motor (40, 42) is a hydraulic motor.