DE8906700U1 - Drive unit for an industrial truck, in particular for a pallet truck - Google Patents

Description

iL HIiRTH 29.5.1989 /

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Drive unit for a forklift truck for a pallet truck

State of the art

The invention relates to a drive unit for an industrial truck, which essentially consists of an E-motor, a two-stage gearbox and a drive wheel and can be accommodated in the chassis of the industrial truck so as to be pivotable about a vertical axis, the drive element of the first gearbox stage being mounted on the output shaft of the electric motor and the output element of the second gearbox stage being mounted on a horizontal output shaft, one end of which projects out of the gearbox housing and accommodates the drive wheel.

Such a drive unit is known from OE 31 33 027 C2, among others. In this known design, the two-stage transmission is designed as a spur gear-bevel gear, whereby the E-motor is mounted coaxially with the swivel axis on the transmission housing and whereby a swivel bearing that accommodates the transmission housing in the chassis of the industrial truck surrounds the E-motor.

This design has proven to be the best* for industrial trucks such as forklift trucks and the like. The relatively high costs for the swivel bearing must be taken into account. For vehicles with lower performance, such as pallet trucks, the known design is too expensive.

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In these vehicles, which are steered manually using a drawbar, the reaction torque from the drive to the steering also has a detrimental effect.

Task

The invention is therefore based on the object of developing a drive unit of the type mentioned at the beginning, in which the drive energy does not have to be passed through the swivel bearing, i.e. no reaction force from the drive should act on the steering and a cost-effective swivel bearing should be able to be used.

Solution and benefits

The solution to the problem provides a drive unit with the features of the main claim. The subclaims show useful embodiments.

In the drive unit according to the invention, thanks to the shafts arranged parallel to one another (output shaft of the Egr; motor, pinion shaft, output shaft), no reaction torques from the drive act on the steering. The drive energy is also not passed through the swivel bearing, so that it does not have to be larger than is necessary for its actual task.

In order to keep the enveloping circle, i.e. the space required by the drive unit when pivoting around the vertical pivot axis, (to as small as possible, the design according to claim 2 is useful.

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The first gear stage can be designed as a spur gear stage (claim 3) or as a traction drive (claim d), the latter being advantageously designed as a toothed belt drive (claim 5). The toothed belt is not only advantageous in terms of noise development, but it also enables the center distance, which depends on various factors, to be bridged with toothed belt pulleys of a smaller diameter than is possible with gears. Since the toothed belt drive is not lubricated, a light metal cover is sufficient to cover it, which, in conjunction with the small diameters, has a positive effect on the envelope circle (claim 6). From this point of view, the measure of providing grease lubrication for the second gear stage must also be considered, since the sealing surfaces otherwise required with oil lubrication would require additional space and increase the envelope circle.

To change the ratio of the first gear stage, it is sufficient to use a different drive element (pinion or first toothed belt pulley); the output element and, if applicable, the toothed belt can remain unchanged if the Egr; motor is attached to a swing arm according to claim 7 and the axle distance can be varied in this way.

Appropriate designs for the swivel bearing are specified in claims 8 and 9. For use in pallet trucks, the drive unit is suitably designed according to claim.

If the industrial truck does not have its own braking devices, but these are to be attached to the drive unit, then the designs according to claims 11 to 13 offer space-saving yet operationally reliable solutions.

Another way to integrate a brake into the drive unit is to use a sliding armature brake in conjunction with a friction brake (claim l4),

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which is conveniently designed as a cone brake,

Drawings

The invention is described below using two exemplary embodiments, which are shown in 5 figures. They show

Fig. 1 shows a pallet truck in which the inventive
drive unit is applicable,

Fig. 2 shows a longitudinal section through an inventive
drive unit,

Fig. 3 a side view in the direction of arrow III,

Fig. k a cross-section approximately along the line IV-IV,
and

Fig. 5 shows a variant of the embodiment according to Fig. 2 in a simplified representation.

Description

In Fig. 1, a so-called pallet truck 1 is shown as an example of an industrial truck. Its chassis 2 accommodates a drive unit 10 which can be pivoted about a vertical axis lk and essentially consists of an electric motor 11, a gear 12 and a drive wheel 13. A drawbar 15 is arranged on the drive unit 10, with which the pallet truck can be steered by a person and which can be pivoted about an axis 15A parallel to the axis 13A of the drive wheel 13. In the vertical position shown
In this position, the drawbar acts on a holding brake (not shown here), which is released when the drawbar 15 is tilted (dashed contour), ie in the "drive" position. Except

Two non-steerable rollers are provided for the drive wheel 13. A lifting mast k is arranged on the chassis 2, on which a lifting fork 5 is guided so that it can be adjusted in height to pick up a load 7. The devices required for this, as well as the battery for the electric motor 11, are housed under a hood 8.

The drive unit 10 is shown in Figures 2 to 6. A downwardly extending two-part pivot pin io is screwed onto the chassis 2 and receives the inner ring of a pivot bearing 17 with which a gear housing 18 and thus the entire drive unit 10 is arranged on the chassis 2 so as to be pivotable about the vertical pivot axis tk . The gear housing 18 is provided with a pot-shaped attachment 19 for receiving the outer ring of the pivot bearing 17. For steering-geometric reasons, the pivot axis 1k lies at least approximately in a central rotation plane 39 of the drive wheel 13. A support arm projects upwards from the gear housing 18 or the attachment 19, to which the electric motor 11 is attached with screws 21.

A first toothed belt pulley 23 is placed on the output shaft 22 of the electric motor 11 and is held in a rotationally fixed and axially fixed manner by a nut 26. A second toothed belt pulley 25, also rotationally fixed and axially immovable, is placed on a pinion shaft 29 which is rotatably mounted in the gear housing 18 and in a bearing plate 28 by means of roller bearings 26, 27. The pinion 30 of this second toothed belt pulley meshes with a spur gear 311 which is again rotationally fixed and axially immovable and is placed on an output shaft 32. The output shaft 32 is rotatably mounted in the gear housing 18 by means of a roller bearing 33. Its end facing away from the spur gear 31 projects out of the gear housing 18 and carries the drive gear 13 which is fastened with screws Jk .

The first toothed belt pulley 23 and the second toothed belt pulley 25 are connected to one another via a toothed belt 35. These parts together form a first gear stage 4l, for which no lubrication is required. To protect against damage and coarse dirt and for the safety of the person operating the pallet truck 1, a light sheet metal cover 36 is provided, which is attached to the bearing plate 28 and/or to the gear housing l8.

The gear box j(j ütiu and spur gear ji together form a further gear stage k2, for which grease lubrication is provided. This eliminates the need for space-consuming sealing surfaces, which would be necessary with oil lubrication, so that the bearing plate 28 can also be made of sheet metal. Screws 37 are provided for fastening to the housing.

The compact design of the drive unit 10 and the use of the space-saving bearing shield 28 and sheet metal cover 36 enable an enveloping circle radius 38 which is only slightly larger than the radius *iO of the drive wheel 13. Thanks to this almost optimal enveloping circle, the handlebar is Ho« CX eKWtiHw» «» av* « -t «*&EEgr;&lgr;*~ H Vv &·**-» «»*·*« + A ·» & tX ****** ♦· ^*··-» ~

of an industrial truck equipped with the drive unit 10 according to the invention is made easier. The enveloping circle is not negatively influenced if - as shown in Fig. 2 and 3 - the motor axis HA, the swivel axis ik and the axis I3A of the drive wheel \j lie in a vi., ? ical plane.

The roller bearing 33 of the output shaft 32 is a double-row ball or tapered roller bearing in 0 arrangement. (In Fig. 2 one version is shown below the axis 13A and the other above the axis 13A.' This type of bearing ensures easy installation and high rigidity. As a rule, the same bearing can be used for the swivel bearing, which makes it easier to procure,

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Storage, assembly and spare parts storage is an advantage .

The ratio of the first gear stage 4l can be easily changed by replacing the first toothed belt pulley 23 with one with a different number of teeth. The second toothed belt pulley 25 and the toothed belt 35 can remain unchanged. In order to bridge the changed center distance, a type of swing arm 6l is provided for fastening the electric motor 11 to the support arm 20, which is shown in Fig. 3. Of the two screws 21, the one on the left serves as a pivot point around which the electric motor 11 can be pivoted out of its drawn position. To make this possible, an elongated hole 62 is provided in the support arm 20 for the screw shown on the right. In the pivoted position, the electric motor 11 is fixed in the usual way by tightening the screws 21.

A fork-like drawbar bearing block 43 is cast onto the gear housing 18, in which the drawbar 15 is pivotably mounted about the axis 15A parallel to the axis 13A. The drive unit 10 can be pivoted about the vertical pivot axis 14 by means of the drawbar 15, and the vehicle can thus be steered. The drawbar 15 can also be used as a "brake lever" for releasing a holding brake 44 designed as a spring-loaded drum brake. The principle of such spring-loaded brakes is known (e.g. from H. Ernst: Die Hebezeuge, Verlag Friedr. Vieweg fc Sohn, 1965, Volume I, pages 105/106), which is why the holding brake 44 is not shown in all details. The second toothed belt pulley 25 is simultaneously designed as a brake drum, against which two brake shoes 46, 47 act under the action of a spring (not shown).

To release the holding brake 44, the drawbar 15 is moved from the vertical position to an inclined position (dashed contour in Fig. 1). In doing so, a cam 48 presses against

the drawbar 15 on a lever k9 mounted in the gear housing l8, which is connected on an actuating shaft 6θ in a rotationally fixed manner to an element 50 which acts against the said spring when rotated.

A brushless DC motor or a frequency-controlled AC inverter can be used as the electric motor 11.

A variation of this is shown in Fig. 5, where a sliding armature motor 51 with integrated conical disk brake S2 is used between the electric motor 11 and the stop brake kk . Sliding armature motors are also known (loc. cit., pages 132/133), which is why it is only shown schematically. When the motor 51 is de-energized, a spring 53 presses the motor shaft 5k together with the armature and a brake cone in the sense of Fig. 5 to the right against a corresponding braking surface 56 in the motor housing. As soon as the motor 51 is switched on (the corresponding switches are arranged on the handle of the drawbar 15 - as is the case for the electric motor 11 - but they are not shown), the conical armature is pulled to the left by the magnetic effect of the stator winding, which is also conical, whereby the conical disk brake 52 is released. The axial displacement of the armature and thus of the motor shaft 5k also requires a brushless design for the sliding armature motor 51.

Due to the axial displaceability of the motor shaft 5^, the guide disks 63 must be provided on the second toothed belt pulley 25 instead of on the first toothed belt pulley 23 and/or the first toothed belt pulley 23 is then arranged on the motor shaft ⁵¹ * so as to be axially movable relative to the latter.

Instead of the traction mechanism 23, 25, 35, a spur gear can also be used for the first gear stage 1, as shown in Fig. 5. A pinion 57 is arranged on the motor shaft 5*i, which is connected to a

the pinion shaft 29 interacts with the spur gear 58. If the pinion 57 meshes directly with the spur gear 58, both parts must have relatively large diameters (larger than the toothed belt pulleys 23, 25 in Fig. 2i) in order to be able to bridge the center distance of the first gear stage 4l. The consequence of this is a larger filling area than is shown in Fig. k . Therefore, an intermediate gear 59 is provided which, with the same total center distance, enables smaller diameters for the pinion 57 and the spur gear 58 and , as a result, a smaller enveloping circle similar to that shown in Fig. 4.

If the first gear plate kl is designed as a spur gear drive, the spur gear 58 can be designed as a brake drum or holding brake in the same way as described above for the second toothed belt pulley 25. If the pinion 57 is arranged on the motor shaft 54 of the sliding armature motor 351, it should be wider than the intermediate gear 59 or spur gear 58 meshing with it by at least the length of the axial displacement of the motor shaft 5k , in order to keep the latter always in engagement over its entire tooth width.

The essential points of the drive unit according to the invention are, as can be seen from the description, to be regarded as:

1) The electric motor 11 or the sliding armature motor 51 is arranged transversely above the drive wheel 13 or the pivot bearing 17. As a result, the motor 11, 51 has no negative influence on the enveloping circle radius 38.

2) In order to bridge the relatively large center distance, the use of a modern HTD toothed belt is recommended for the first gear stage kl - in addition to other means such as the spur gear drive 57, 58, 59. The relatively low torques in the first stage allow the toothed belt to be dimensioned favorably in relation to the installation space.

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Further advantages of this concept are the favorable wrap angle resulting from the center distance and the possibility of being able to vary the gear ratio via an adjustable center distance by using first toothed belt pulleys 23 with different numbers of teeth, whereby the toothed belt 35 and the second toothed belt pulley 25 remain the same.

3) For the second gear stage k2, a spur gear drive can be accommodated within the actual gear housing l8, the pinion 30 and spur gear 31 of which are case-hardened due to the high stress.

k) The bearing for the drive gear 13 can be provided with an adjusted and sealed bearing unit (double-row roller bearing 33) within the actual gear housing 18. This solution makes it possible to manufacture the bearing plate 26 in a space-saving and cost-effective manner from sheet metal. The output shaft can be connected to the spur gear via a (tapered) interference fit, which simultaneously provides the axial fixation of the two-part bearing inner ring.

5) The drum brake integrated into the second toothed belt pulley 25 or the spur gear 58 is essentially a holding brake in terms of its function. As a service brake, it is usually only used in the lower speed range. It is actuated by a spring accumulator and released by the cam 48 on the drawbar 15. The heat generated during emergency braking is absorbed by the mass of the "brake drum", with the toothing having a positive effect on heat dissipation.

Further advantages of integration into the toothed belt pulley 25 or into the spur gear 58 are: the diameter and width of the toothed belt pulley are so sensitized this is the Bress? without "••'st-i.v*

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influencing the installation space, and the actuating shaft 60 can be led out from the side of the spur gear, thus also without influencing the installation space.

6) The swivel bearing 16 is simply accommodated by the gearbox housing 18 and the swivel pin 17 is attached to the chassis using screws. The design criteria for the swivel bearing 17 are the load from the hand load and a superimposed tilting moment from the traction force. The arrangement directly above the drive wheel 13 reduces the tilting moment to a minimum. The same sealed, adjusted bearing unit is used as the bearing for the drive wheel 13.

7) The drawbar bearing block 43 is attached below the swivel bearing 17 on the gearbox housing l8 and is made in one piece with it. This eliminates the need for additional separating parts. The low pivot point for the drawbar 15 takes safety regulations into account in that the steep drawbar arrangement means that the operator cannot be trapped between an obstacle and the vehicle 1 when reversing.

The invention allows for further variants that fall within the wording of the claims and that should also fall within the scope of the protection right.

List of terms

1 pallet truck

2 Chassis

3 Role

k Lifting mast 5 Lifting fork b

7 Load
α ii _ j. u _£

10 Drive unit

11 Electric Motor

HA Axle of

12 Gearboxes

13 Drive wheel 13A Axle of \k Swivel axis

15 Drawbar

15A Swivel axis of

16 pivot pins

17 Swivel bearing

18 Gearbox housing

19 Essay

20 Support arm

21 Screw

22 Output shaft of

23 first timing belt pulley 2k nut

25 second timing belt pulley

26 Vfä: ilager

27 rolling bearings

28 Bearing shield

29 Pinion shaft

30 pinions

31 Spur gear

32 output times of

33 rolling bearings

34 Screw

35 Timing belt

36 metal lids .

37 Screw

38 Envelope radius

39 Rotation plane of 13 kO Radius of 13 /14 _ — _4-» nM% *■ wi 0KO ·. *■ ·■ fm

k2 second gear stage kj drawbar bearing block

kk Holding brake 1*5 k6 Brake shoe kl Brake shoe &Iacgr;8 cam ^»9 lever 50 element 51 Sliding armature motor 52 Conical disc brake 53 Feather 5k Hoiorweiie 55 Brake cone 56 Braking surface 57 pinion 58 Spur gear 59 Intermediate gear 60 Actuating shaft 61 Swingarm 62 Long hole 63 Guide disc

Claims (13)

&igr; · &igr; · • · I · a Claims 1) Drive unit for an industrial truck, which essentially consists of an electric motor (11), a two-stage gearbox (12) and a drive wheel (13) and can be pivoted about a vertical axis (δ) in the chassis (2) of the industrial truck, wherein the drive member of the first gearbox stage (41) is mounted on the output shaft (22) of the electric motor (11) and the output member of the second gearbox stage (k2) is mounted on a horizontal output shaft (32), one end of which projects out of a gearbox housing (18) and receives the drive wheel (13), characterized in that that the electric motor (11) is arranged axially parallel to the output shaft (32), that the output member of the first gear stage (41) is mounted on a pinion shaft (29) of the second gear stage (k2) mounted in the gear housing (l8), and that a pivot bearing (17) is arranged above the drive wheel (13), the outer ring of which is accommodated in the gear housing (l8) and the inner ring of which is placed on a pivot pin (l6) extending downwards from the chassis (2), the axis (pivot axis ik) of which lies at least approximately in the central rotational plane (39) of the drive wheel (13), the electric motor (11) projecting beyond the area of the chassis (2) having the pivot pin (l6). 2) Drive unit according to claim 1, characterized in that the rotation axes (HA, 13A) of the E-motor (H) and of the drive wheel (13) as well as the pivot axis (ilk) lie at least approximately in one plane. 3) Drive unit according to claim 1 or 2, characterized in that the first gear stage (kl) is a spur gear stage with a pinion (57) as drive member and a spur gear (58) as output member. k) Drive unit according to claim 1 or 2, characterized in that the first gear stage (kl) is formed by a traction mechanism transmission. 5) Drive unit according to claim k, characterized in that the traction mechanism is a toothed belt drive with a first toothed belt pulley (23) as drive member and a second toothed belt pulley (25) as output member. 6) Drive unit according to claim k or 5, characterized in that the second gear stage (k2) runs in a gear chamber formed essentially by the gear housing (l8) and by a bearing plate (28) with grease lubrication, and that the non-lubricated traction mechanism of the first gear stage (k1) is covered on the outside outside this gear chamber by a light sheet metal cover (36) fastened to the bearing plate (28) and/or to the gear housing (l8). 7) Drive unit according to one of claims 1 to 6, characterized in that the electric motor (11) is connected to the gear housing (18) by means of a gear housing (18) articulated, I ft
·· ·
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·· about an axis which is parallel to the axis of rotation (HA) of the ε-motor (11) and displaced relative to the plane defined by the other axes (13A, Ik) and is pivotably adjustable. 8} Drive unit according to one of claims 1 to 7, characterized in that the pivot bearing (17) is a double-row rolling bearing with rolling elements in 0-arrangement. 9) Drive unit according to claim 8, characterized in that the output shaft (32) is mounted in the gear housing (18) with a roller bearing (33) identical to the pivot bearing (17). 10) Drive unit according to one of claims 1 to 9, characterized by a drawbar bearing block (43) arranged on the outside of the gear housing (18) for receiving a drawbar (15). 11) Drive unit according to one of claims 1 to 10, characterized in that the output member of the first gear stage (kl) is designed as a brake drum of a drum brake (holding brake kk) . 12) Drive unit according to claim 11, characterized in that the drum brake (holding brake kk) is designed as a spring-loaded brake which can be released from the outside via a lever (49) acting against the spring. ••■111 ' ■ · 13) Drive unit according to claim 10 in conjunction with the feature of claim 12, characterized in that the drawbar (15) is provided in the region of its receptacle in the drawbar bearing block (C*3) with a cam (48) which, in the drawbar position "drive" (drawbar (15) is inclined to the roadway), presses the lever (49) into the "release brake" position and which, in the drawbar position "stop" (drawbar is vertical), presses the lever (49) into the "apply brake" position (spring accumulator is released). Drive unit according to one of claims 1 to 10, characterized in that the i-motor (11) is designed as a sliding armature motor (51) combined with a friction brake (conical sliding brake 52).