Industrial truck, in particular forklift truck

0001The invention relates to an industrial truck, in particular fork lift truck, with a Drive part and a load part, wherein in the region of the load part at least two Lastrollen and in the area of ​​the drive member at least one steerable wheel and at least one caster being arranged, rotatably about a vertical axis and is arranged vertically movable and by means of a spring-damper device is supported.

0002Such Handling for example, as a pedestrian-controlled pedestrian operated trucks known or truck with a platform or a seat. The last part such a truck is by means of two load rollers on the road supported. The driving part is supported with the drive, which is preferably rigidly attached The truck is fixed onto the Farbahn. To increase stability on Driving part at least a caster provided vertically movable and is rotatably mounted on the drive part. Here, constructions are known in which the Drive wheel is arranged at a distance to the vehicle longitudinal sides and on the opposite side at a distance from the vehicle longitudinal axis Caster is arranged. Besides such truck with a Four wheel chassis trucks are also known with a five-wheel chassis, in which the drive wheel is mounted centrally on the drive member and two castors spaced apart on the sides of the drive member to the vehicle longitudinal axis are arranged.

0003The casters are means of a spring-damper device on the roadway supported, the spring of the spring-damper device which the wheel contact counteracting support force on the caster determined. By suspension of is pivotal roles the truck to an oscillatory system, wherein for vibration damping, the spring-damper device having a damping means is provided.

0004A generic industrial truck is known from DE 197 53 412 C2. The Caster is mounted in a about a horizontal axis pivotable rocker, at a coil spring engages. From the deflection of the spring is that of Wheel force counteracting support force on the caster determined. As Damping means are hydraulic cylinder shock absorber provided laterally are arranged next to the supporting role to the rocker. The cylinder Shock act at a deflection of the caster. With a rebound of Caster unfold the cylinder shock absorber no dampening effect. hereby it may in particular when cornering the truck at the inside of the curve Caster by a decreasing wheel loading to a fast Rebound come and by the action of a helical spring, the inclination of the Truck supporting power occur, whereby high roll angle of Truck may occur to the truck longitudinal axis to a perform small tilting stability of the industrial truck. In addition, due to the of the coil spring certain supporting force of the pivotal role in such Operating state, the wheel load of the drive wheel is reduced, resulting in lower braking and Driving forces to be transmitted and thus the truck in particular during cornering have a low stability. Due to the rapid and undamped springing the pivotal role in a vertical wheel changing also occurs several times overshoot before an equilibrium state is achieved between the wheel force and the support force. A multiple Overshoot until a stable roll angle during a Cornering leads to low stability of the industrial truck.

0005The present invention has for its object, a truck of initially to provide kind mentioned are available, the improved stability having.

0006This object is achieved in that the spring-damper device one with a rebound and a deflection of the caster effective damping means, in particular a hydraulic damping means, having and / or the spring-damper device has a progressive spring characteristic having. With such an, in particular hydraulic damping means, the Ausfederungsgeschwindigkeit and the shock is compressed the caster be limited, whereby a controlled Einfederverhalten and rebound characteristics the castor can be achieved. When cornering or driving an uneven road surface can thereby the overshoots in a changing wheel loading can be improved and a multiple Overshoot can be avoided. Through a progressive spring characteristic of the spring-damper device can with little effort a progressive with increasing Deflection rising, the wheel force counteracting support force of Caster be achieved, wherein during extension of the pivotal role the supporting force disproportionately decreases and during compression of the caster the supporting force increases disproportionately. By such a behavior of the castor can be a high driving stability of the truck by low roll angle, for example, during cornering, and high transmittable from the drive wheel brake and Driving forces are achieved. This results in overall improved stability and improved drivability of the truck, whereby the maximum Driving speed of the truck in the laden and unladen condition at Obtaining the necessary vehicle stability are raised in all driving conditions can.

0007According to a preferred embodiment of the invention, the damping means is of at least an effective during compression throttle device and at least one formed during rebounding effective throttle device. can with restrictors easily a hydraulic damping means are provided, the case of deflection and rebound damping of the castor allows.

0008Conveniently, the spring-damper device according to a preferred Embodiment of the invention, a first oil-filled space, the volume of the deflection or rebound of the caster is dependent and the means of Throttle means communicates with a compensation chamber in communication, and a second oil-filled space in which the volume of the spring deflection or rebound of Caster is dependent and the means of a throttle device with the first Space and / or by means of a throttle device with the expansion chamber in Connection is. With such an arrangement it is possible in a simple manner, a jounce and effective during rebounding space available to questions and thus the shock is compressed and Ausfederungsgeschwindigkeit the caster via appropriate attenuate restrictors, whereby during compression and in rebound the caster effective damping means is obtained.

0009Appropriately, is the first space via a toward the first space opening shut-off valve device, in particular a check valve, with the Compensating chamber in conjunction. It can hereby be achieved, that during rebounding Pressure fluid through the open check valve means from compensating chamber in the flows first space and thus the damping of Ausfederungsgeschwindigkeit over the second chamber to the first chamber and / or the compensation chamber connecting restrictors done.

0010If according to a preferred embodiment of the invention in the second Room a standing with the castor wheel operatively connected damping piston is arranged, can with a little construction or of the deflection scored rebound of the castor-dependent volume of the second space will.

0011A progressive spring characteristic and thus a progressive course of the supporting force the pivot roller can in accordance with a preferred embodiment of the invention easily be achieved if the compensation chamber under a gas charge can be brought. By compressing the gas in the expansion chamber during Compression of the caster can easily create a progressive spring force and thus supporting force of the caster can be achieved. In addition, by changing the gas preload the spring-damper device in a simple manner to different types are adapted from trucks.

0012Appropriately, in the first oil-filled space with a pivotal role in Operative connection spring of the spring-damper device arranged. By Assembly of the caster spring acting in the first room gives a low space requirement.

0013If in a preferred embodiment of the invention, a further spring is provided in the from a predetermined spring deflection with the castor wheel Can be operatively connected, can with little effort a progressive support force be achieved.

0014Suitably, the additional spring is disposed in the first oil-filled space, resulting in a low space requirement.

0015Particular advantages result when the compensation chamber in accordance with a Development of the invention a towards the compensation chamber opening Shut-off valve, in particular a non-return valve, with a container in connection stands. Leaks in the first space, the second space and the compensating space, which at Rebound of the caster to a drop in gas pressure below the lead ambient pressure, can thus be compensated automatically, whereby the spring-damper device has a high reliability.

0016According to an advantageous embodiment of the invention is the pivotal role with a piston-like assembly in conjunction, the cylindrical in a Member is longitudinally displaceably mounted, in which the first space, the second space and the compensation chamber is formed. This configuration of the spring-damper device as cylindrical assembly I results in a low cost of construction and Space requirement.

0017Conveniently, on the cylindrical part a first chamber and the is arranged equalizing space limiting device in which the second space is trained. With such a device can at low construction cost in the cylindrical part of the first space and the compensating space and the second space are formed.

0018Particular advantages are obtained if, according to an advantageous embodiment, the invention in the device, the first chamber with the compensating chamber connecting throttle means and / or the second space with the Equalization chamber connecting throttle means and / or the second space with connecting the first space throttle means and / or the first space with the compensation chamber connecting locking valve means and / or the Compensation chamber with the container disposed connecting check valve. In the Device can be connected to the corresponding spaces Restrictors and check valves are arranged with little effort. Therefore, by training all restrictors and check valves in the component in a simple manner by changing the throttle means in the device, the adapted spring-damper device to different types of trucks will.

0019A simple construction of the cylindrical component arises here when the cylindrical member has a first delimiting the base body and a the compensation chamber delimiting lid which cooperates with the base body is connectable, wherein between the base body and the lid, the device is located and secured. The component can thus easily be clamped between the base body and the lid.

0020The connecting the first chamber to the compensation chamber throttle device and / or check valve device can easily in the component are formed when according to an advantageous embodiment, in the A device connecting the compensation chamber to the first chamber Connection channel is formed, in which the throttle device, in particular a Throttle, is arranged and / or in the device, a compensating space with the first connecting space connecting duct is formed, in which the Spemrentileinrichtung, in particular a check valve, is arranged. In addition, it is possible, the throttle means and the check valve means to a Flow control valve to summarize and in a connecting channel Component to arrange.

0021For connecting the second chamber to the first chamber throttle device resulting in a simple arrangement when in the device a second space is formed with the first connecting space connecting duct, in which the Throttling device, in particular a throttle, is arranged.

0022The second room with the compensation chamber connecting throttle device can be provided in a simple manner when the second space of one with the standing equalization chamber in conjunction hole shaped recess of is component formed in the damping piston is arranged, said the second room with the compensation chamber connecting throttle means of a Annular gap is formed between the damping piston and the recess.

0023The connection of the compensation chamber with the container can low Constructional be produced if in the device according to a expedient embodiment of the invention, formed an annular groove with a lid formed in the channel, which is connectable to the container, in Connection, where the one in the device of the annular groove to is formed equalizing space owned connecting channel, in which the shut-off valve, in particular a check valve, is arranged.

0024A simple connection of the damping piston with the pivotal role arises, if expediently the damping piston by a piston rod, which in is guided to the component, in communication with the piston-shaped unit.

0025Further advantages and details of the invention will become apparent in the schematic figures illustrated embodiment explained in more detail. It shows<dl tsize="7"><dt>figure 1</dt><dd>an inventive truck in a side view,</dd><dt>figure 2</dt><dd>a driving part of an industrial truck according to the invention in a schematic rear view, and</dd><dt>figure 3</dt><dd>a pivotal role in a longitudinal section.</dd></dl>

0026In the figure 1 is designed as a drawbar-guided high-lift pallet truck Truck 1 shown, which comprises a drive part 2 and a load part. 3 The Drive part 2 has with respect to the longitudinal axis of the truck 1 a centrally disposed drive wheel 4 and two laterally arranged pivotal rollers 5a, 5b. The drive wheel 4 can be steered by a tiller. 6 The last part includes 3 Supporting arms 7, which up to a lifting frame 8 and are arranged movable up. Of the Last part 3 further comprises two support arms 9, in each of which a single roller or tandem roller trained load roller is mounted 10th The truck 1 is based thus by means of the drive wheel 4, the pivot rollers 5a, 5b and the load rollers 10 onto a road 11th

00272 shows the schematic structure of the drive part 2 of the truck 1 according to the figure 1. The steerable drive wheel 4 is centered on the longitudinal axis of the Truck mounted on not illustrated manner on the drive part. 2 To both sides of the drive wheel 4 is spaced from the longitudinal axis of the Truck each pivotal role 5a, 5b attached to the driving part. 2 The Caster 5a, 5b is in this case respectively by means of a spring-damper device 12a, 12b supported on the roadway eleventh

0028In the figure 3 is caster 5a, 5b with a spring-damper device 12a, 12b Longitudinal section shown. The caster 5a, 5b is in a suspension 20 to a horizontal axis 21 is rotatably supported. The suspension 20 is by means of a bearing 22, in particular a rolling bearing, about a vertical axis 23 for rotation in a piston-like assembly 24 mounted. The piston-like assembly 24 is in a cylindrical part 25 of the spring-damper device 12a, 12b in the direction of vertical shaft 23 mounted longitudinally.

0029The cylindrical component 25 consists of a base body 25a in the lower Area is provided with a flange 25c for attachment to the drive part 2, and a lid 25b 25a no longer shown manner with the base body connected is. The base body 25a and the cover 25b are attached to the side region facing each one formed by a bore paragraph flange provided, wherein a component arranged between the flanges 26 and by the connection of the cover 25b is fixed to the base body 25a.

0030In the base body 25a is of the piston-shaped component 24 and the component 26, a first chamber 30 is formed, in which a pivotal role 5a, 5b which acts Spring is arranged 27th In the first space 30, a further spring 28 is disposed, which is spaced from the component 26 and from one of this decency predetermined deflection d1 with the castor wheel 5a, 5b brought into operative connection is.

0031The lid 25b and the building element 26 define a compensation chamber 31, which via designed as a choke inductor 32 and a as towards the first space 30 opening, designed as a spring-loaded check valve Blocking valve device 33 is connected to the first space 30th The Throttling device 32 is in this case in one of the expansion chamber 31 to the first Space 30 out connection line 34 which in the device 26 is trained. arranged in a further in the device 26. Connecting channel 35, which connects the compensating space 31 with the first space 30, disposed check valve means 33rd

0032The equalization chamber 31 is also connected to a container 36 in conjunction. In that regard, an annular groove 37 formed on the component 26 associated with one in the lid 25b formed channel 38 is connected, which is connected to the container 36th In the component 26 an annular groove 37 which connects with the expansion chamber 31 Connecting channel 39 is formed, in which a spring-loaded check valve as trained, opening towards the compensation space 31 check valve 40 is arranged.

0033In the device 26 a second space 41 is formed, of the with of an Equalization chamber 31 communicating hole shaped recess 42 is formed. In device 26 a connecting channel 43 is further arranged the is guided by the bore end of the recess 42 for the first space 30th In this Connecting channel 43 is designed as a throttle throttle device 44 arranged.

0034In the second space 41, a damping piston 45 is arranged, which in a the component 26 guided piston rod 46 with the piston-shaped part 24 and Thus the caster 5a, 5b is connected. Between the bore-shaped Recess 42 and the damping piston 45 is formed an annular gap which has a the second space 41 connects with the compensating chamber 31 throttle device 47 forms.

0035In the illustrated starting position of the caster 5a, 5b of the first space 30 and the second space 41 completely filled with pressure medium, for example oil. Of the Compensation chamber 31 is filled up to the level 48a with pressure medium. The equalization chamber 31 continues to be brought under a gas charge. For this purpose in the cover 25a with a the expansion chamber 31-related channel 49 provided.

0036In the initial position shown is the supporting force of the swing roller 5a, 5b constant according to the predetermined on the truck by means of springs 27, 28 and the gas pressure in the equalization chamber 31 adjustable deflection d.

0037With a deflection of the swing roller 5a, 5b in the direction 50 of figure 3 by a increased tire contact force is the piston-shaped part 24 urged upwards, which pressure medium from the first space 30 via the throttle device 44 in the second space 41 and flows via the throttle device 32 into the compensating chamber 31st At maximum deflection d, the pressure medium in the compensation chamber 31 is on the level 48b. Due to the increase of the pressure medium in the compensation chamber 31 increases the gas pressure force on the equalization chamber 31st By the springs 27, 28 and the Gas pressure in the compensation chamber 31 is with increasing compression progressively Spring characteristic and thus achieves a progressively increasing support force. By Action of the throttle means 32 and 44 in this case is the damped shock is compressed the caster 5a, 5b and a multiple Overshooting of up to reaching an equilibrium state between Supporting force and the wheel contact avoided, whereby a controlled Deflection behavior of caster 5a, 5b results. This may in particular when cornering the truck by a slight deflection of the outside curve caster a small roll angle about the vehicle longitudinal axis at high driving stability of the industrial truck can be achieved.

0038With a rebound of caster 5a, 5b in the direction 51 of figure 3 due a decreasing wheel force is the piston-shaped part 24 to the Figure 3 is exposed below. Pressure fluid flows out through the expansion chamber 31 via the opened shut-off valve means 33 in the first space 30. In order to damp the Ausfederungsgeschwindigkeit the caster 5a, 5b, the damping piston 45 provided, which during rebound to about the piston rod 46 in the Figure 3 below is pressurized and pressure medium from the second space 41 via the Throttle means 44 in the first space 30 and over the annular gap as designed throttle device 47 displaced into the compensation chamber 31st hereby high Ausfederungsgeschwindigkeit can be avoided and the cavitation Pressure means the overflow of the expansion chamber 31 in the first chamber 30 be avoided. can therefore through the damping piston 45 a controlled be achieved Ausfederungsverhalten the caster 5a, 5b. In this way, especially during cornering of the industrial truck a repeated Overshoot can be avoided and thus a stable handling of be truck achieved with low roll angle. By from the Compensating chamber 31 flowing pressure medium takes the gas pressure in the equalization chamber 31 progressively, so that during rebounding the supporting force of the caster 5a, 5b progressively decreases. Hereby is achieved during cornering, that at the inside curve caster a small support force occurs, thereby providing a high Wheel load of the drive is available. can therefore at the drive high Braking and driving forces are transmitted, whereby the truck in particular when cornering has a high driving stability.

0039If due to a leak in the spring-damper device 12a, 12b, the Oil volume decreases in the compensation chamber 31, falls during rebound of the pivot roller 5a, 5b of the upcoming in the compensation chamber 31 gas pressure below the ambient pressure. about the check valve 40 can in this case automatically the pressure medium from the container 36 into the Equalization chamber 31 subsequently flow to compensate for the leakage.