Drive System of a Drive Wheel

The invention concerns a drive system of a drive wheel, which is suitable in particular for vehicles and their trailers as an auxiliary drive system for a drive wheel/drive wheels.

From the EP Patent Application 0,562,122, a drive system for a wheel of a vehicle is known in which a motor is fitted to rotate planetary gears through its output shaft and which system comprises a stationary peripheral gear. A braking element is fitted between a stationary frame and the frame of the wheel hub which is fitted to revolve. The construction of this solution is rather complex, because the positioning of the brake element requires space. Also, it is a drawback of the drive system that in the free run position the shaft of the hydraulic motor is still rotated, and said rotation can be disengaged exclusively if a separate coupling is provided between the output shaft of the motor and the shaft that operates the central sun gear.

In the present application, a simple drive system for a drive wheel is suggested in which the drawbacks mentioned above are avoided. In the present invention, it has been realized to use a planetary gear system in which the peripheral gear is operationally connected with a clutch. In the construction in accordance with the invention, the clutch is fitted between a sleeve shaft that acts upon the peripheral gear and the motor frame. In the system, the motor is fitted, in a way in itself known, to operate the planetary gears, and the planetary gears are coupled with the wheel hub. According to the invention, when the wheel is driven and when the drive is passed to the wheel, both the clutch is engaged and the shaft of the motor is switched on to revolve. Thus, when the clutch is engaged, the outer peripheral gear is kept locked and the drive is transferred through the planetary-gear frame to the wheel hub.

When braking is operated, the motor is switched off and locked, and the clutch/brake is kept engaged. Then, the clutch operates as the brake and carries out the braking of the wheel. Thus, the braking does not produce any torque in the hydraulic motor.

In free operation, both the clutch is kept in the free position and the hydraulic motor is kept non-operated.

The drive system in accordance with the invention is mainly characterized in that the peripheral gear is fitted to revolve, and the toothing on the peripheral gear is connected with a separate sleeve shaft, which is fitted to surround the output shaft rotated by the motor, and that the sleeve shaft is journalled to revolve, and that there is a clutch/brake element between said sleeve shaft and the frame, in which case, when the clutch is engaged and when the motor is in operation, the drive is passed to the wheel, and when the motor has been connected out of operation and the clutch is engaged, the wheel is being braked, and when neither the clutch is engaged nor the motor is in operation, the wheel is in the freely revolving state.

The invention will be described in the following with reference to some preferred embodiments of the invention illustrated in the figures in the accompanying drawings, the invention being, however, not supposed to be confined to said embodiments alone.

FIG. 1 is a side view of a bogie construction of a trailer.

FIG. 2 shows the construction of FIG. 1 viewed from above.

FIG. 3 shows the bogie construction viewed in the direction of the arrow k.sub.1 in FIG. 1.

FIG. 4 shows a hydraulic drive system in accordance with the invention, being a sectional view of a hydraulic-motor planetary-gear assembly.

FIG. 5 shows an embodiment of the invention which is in the other respects similar to the embodiment shown in the former figures but in which the brake operation is different.

FIG. 1 shows the bogie 10 at one side of the trailer of a vehicle, comprising the wheels 11a.sub.1 and 11a.sub.2 in the bogie construction. For each wheel 11a.sub.1,11a.sub.2 there can be a separate wheel drive 12a.sub.1 and 12a.sub.2 of its own. It is also possible that one wheel 11a.sub.1 or 11a.sub.2 only is provided with a separate wheel drive. Said wheel drives 12a.sub.1,12a.sub.2 are preferably auxiliary drive systems, which can be switched off when necessary, in which case the wheel drives are in the free position. By means of said wheel drives 12a.sub.1 and 12a.sub.2 it is also possible to carry out braking of the vehicle.

FIG. 2 shows the wheel drive system shown in FIG. 1 as viewed from above. The bogie 10 comprises a swing shaft 13 connected with the suspension R.sub.2 of the bogie mounted on the chassis beam R.sub.1. The swing shaft 13 is connected with a swing beam 14, which includes the wheels 11a.sub.1 and 11a.sub.2 at both ends, together with separate motor drives 12a.sub.1 and 12a.sub.2 for said wheels. The swing beam 14 is fitted to pivot on support of the swing shaft 13.

Each motor drive 12a.sub.1,12a.sub.2 comprises a box 15 connected with the swing beam 14, in whose interior, in the protected space E, there is a hydraulic motor 21.

FIG. 3 shows the solution of equipment viewed in the direction of the arrow k.sub.1 in FIG. 1.

FIG. 4 is a sectional view on an enlarged scale of a wheel drive 12a.sub.1 in accordance with the invention. Said hydraulic auxiliary drive system for a drive wheel of a vehicle, trailer, or equivalent comprises a box-like frame 15 connected with the swing beam 14 of the bogie 10, which frame comprises a first frame part 15a.sub.1 and a second frame part 15a.sub.2 connected with said first frame part by means of screws 16. The wheel hub 19 is mounted to revolve on bearings G.sub.1 and G.sub.2 on the frame part 15a.sub.2 of the frame 15.

The wheel hub 19 comprises a first frame part 19a.sub.1 and a second, outer frame part 19a.sub.2 connected with said first frame part by means of screws 20, and the outer frame part 19a.sub.2 is connected with the rim of the wheel 11a.sub.1.

The motor 21 is placed inside the first frame part 15a.sub.1 of the frame 15 in the space E and is fixed to the frame 15a.sub.1. The hydraulic motor 21 is fitted to rotate the output shaft 22. The output shaft 22 comprises a first shaft part 22a.sub.1 and a second shaft part 22a.sub.2, which comprise, at their ends placed one against the other, grooves or equivalent, from which the shafts are connected with the sleeve D that surrounds them, which sleeve D comprises corresponding inside grooves. The sleeve D is further mounted revolving by means of bearing means 23. Thus, when the shaft 22 is rotated, the sleeve D is also rotated. At the outer end f of the shaft part 22a.sub.2 of the output shaft 22 of the motor 21, there is a sun gear 22b formed out of said end f and comprising a circumferential toothing 22b'. The arrangement of equipment further comprises planetary gears 26a.sub.1 . . . 26a.sub.n, each of which comprises a toothing 26a.sub.1 ',26a.sub.2 ', which is in engagement both with the toothing 22b' on the sun gear 22b of the shaft 22 and with the inner toothing 29' on an outer peripheral gear 29. Each planetary gear 26a.sub.1 . . . 26a.sub.n comprises a shaft 27a.sub.1,27a.sub.2 . . . and a planetary-gear frame 28a.sub.1,28a.sub.2 . . . . Each shaft 27a.sub.1,27a.sub.2 . . . is permanently connected with the hub 19. The planetary gear 26a.sub.1 . . . 26a.sub.n is fitted to revolve around its shaft 27a.sub.1,27a.sub.2 . . . by means of the bearing means T.sub.1,T.sub.2.

In the drive system in accordance with the invention, the wheel hub 19 of the vehicle is connected expressly with the planetary gears 26a.sub.1 . . . 26a.sub.n. On the contrary, the revolving peripheral gear 29, which is in engagement with the planetary gears 26a.sub.1 . . . 26a.sub.n, is connected with the outside sleeve shaft 30 that surrounds the shaft 22 from the flange 30b, from the circumferential toothing 31 on the flange 30b, or equivalent. The sleeve shaft 30 is mounted by means of bearing means 25 and 24 so that it revolves in relation to the box frame part 15a.sub.2 of the box frame 15. The bearing 25 is placed between the tubular extension 15a.sub.2 ' of the frame part 15a.sub.2 and the sleeve shaft 30. The bearings 24 are placed between the sleeve shaft 30 and the flange 36. The sleeve shaft 30 further comprises outside grooves 32 or equivalent, with which the clutch plates 17a.sub.1 . . . 17a.sub.n of the clutch 100 are connected operationally. The other clutch plates 18a.sub.1 . . . 18a.sub.n, which are placed as interlocked with said first clutch plates, are connected with inside grooves 33 or equivalent in the frame 15a.sub.2. The press disk 34 that presses the clutch plates of the system is connected with the flange 36 which extends into the interior of the box frame 15 so that the press disk 34 comprises a projection ring 35b projecting from the flange part 35a, which ring 35b is placed in a ring groove 37 in the flange 36. To the outer face F of the projection ring 35b of the press disk 34, there is a pressure medium connection through the opening 38 in the flange 36. Thus, the operation of the clutch 100 when the traction is switched on or when the braking is switched on takes place by applying the pressure of a medium, for example hydraulic fluid, to the face F of the projection ring 35b. In such a case, the package of plates 17a.sub.1 . . . 17a.sub.n ; 18a.sub.1 . . . 18a.sub.n is shifted in the direction of the arrow L.sub.1 and the plates are locked in relation to one another and, thus, the sleeve shaft 30 is locked in relation to the frame 15. In such a case, the peripheral gear 29 is locked.

By means of the device in accordance with the invention, a smooth free running of the auxiliary power transmission independent from the speed of rotation is obtained. During the free running, the hydraulic motor does not revolve. During braking, a dynamic braking dependent on the braking pressure is obtained.

When the auxiliary power transmission is switched on, the flow of fluid is passed to the hydraulic motor. At the same time, the engagement pressure is passed to the clutch/brake element. If attempts are made to operate the motor 21 with an excessively high pressure, the clutch/brake element operates as a torque limiter.

During braking, the hydraulic motor is locked and braking pressure is passed to the clutch/brake element 100 so as to produce dynamic braking dependent on the braking pressure.

Free rotation is accomplished so that the hydraulic motor is kept free of pressure and mechanically or hydraulically locked, and the clutch/brake element 100 is kept disconnected.

As is shown in FIG. 5, the construction is in the other respects similar to those of the embodiments described above, but the brake unit comprises a separate brake cylinder S. When the brake cylinder S is free from pressure, the spring J of the brake cylinder locks the plates 17a.sub.1,17a.sub.2 . . . ;18a.sub.1,18a.sub.2 . . . , and then the braking takes place when the central shaft is not rotated and its rotation has been locked. When no pressure is passed into the operation duct 380 of the brake cylinder S of the brake plates, the set of gears is locked, provided that, additionally, the shaft 22 is non-revolving and, for example, its drive gear, i.e. the motor 21, is in the locked state. Thus, in this system, the locking in respect of the plates 17a.sub.1,17a.sub.2 . . . ;18a.sub.1,18a.sub.2 . . . is always switched on when no pressurized medium, such as hydraulic fluid, is passed into the duct 380 of the brake cylinder S and, thus, when no control pressure is passed to the brake cylinder S. The plates are kept locked in relation to one another by the spring J at the end of the brake cylinder S. Thus, the system is safe. When pressure is passed into the duct 380, it acts upon the piston part S.sub.10 of the brake cylinder S, which piston part is connected with a spindle S.sub.20, which is surrounded by a press spring S.sub.30. The spindle S.sub.20 is passed through an opening g in the flange part 35b of the press disk 34, and it is fitted to act upon the piston part S.sub.40. The piston part S.sub.40 is further acted upon by the spring J between the piston part S.sub.40 and the end part S.sub.50 of the frame. Thus, when pressure acts upon the piston part S.sub.10 through the medium duct 380, the spindle S.sub.20 connected with the piston part S.sub.10 is displaced so that it acts upon the piston part S.sub.40 and releases the press disk 34 from the force of the spring J, whereby the plates 17a.sub.1 . . . 17a.sub.n ;18a.sub.1 . . . 18a.sub.n become free. If no pressure is passed into the duct 380, the spring S.sub.30 placed around the rod S.sub.20 presses the piston part S.sub.10 into its original position, and the spring J acts upon the piston part S.sub.40, which further applies the force to the flange part 35 of the press disk 34, whereby the plates 17a.sub.1 . . . 17a.sub.n ;18a.sub.1 . . . 18a.sub.n in the package of plates are locked in relation to one another.