The invention relates to a tilting vehicle provided with a first frame section and a second frame section, joined to one another such that they can tilt about a tilt axis located in the longitudinal direction, wherein each frame section is provided with at least one wheel.

A tilting vehicle of this type is disclosed in WO 95/34459 in the name of the Applicant. The rear frame section is provided with two wheels and with a tilting device that comprises two hydraulic cylinders. The front frame section is joined to the rear frame section such that it can tilt and comprises the steering wheel, that is joined via a steering column to a front wheel, as well as the driver's seat. When a bend is taken with the vehicle the moment or the force on the front wheel is measured via a sensor and a control signal is generated that controls the tilting of the front section. The front section is then tilted and when driving round a bend the front wheel is turned slightly outwards until no further moment engages on the front wheel. At that point in time the tilting movement is stopped and the correct angle for tilting the front frame section has been reached, suited to the speed, the radius of the bend and the weight of the driver.

hi WO 99/14099 it is described how the control signal for tilting can be derived from the angle of turn of the steering column with respect to a front wheel tilt axis which is in the plane of the front wheel. Steering of the tilting vehicle takes place not by direct turning of the front wheel by the driver but by operation of the tilting mechanism. When taking a bend, tilting is initiated by the driver, after which the front wheel is turned slightly outwards about its tilt axis. This outward turn with respect to the steering position controls tilting.

In both embodiments of the tilting vehicle described above the drive is in the rear frame section that remains upright on the ground with two wheels. Tilting of the front frame section is also actively driven by a hydraulic, pneumatic or electrical tilting device.

In an alternative embodiment of a tilting vehicle, as described in WO 2004/011324 in the name of the Applicant, tilting of the driver's section can be obtained in a "passive" manner in that the driver braces his feet against a footboard joined to the rear frame section. Tilting can be completely or partially supported by a tilt mechanism and can be damped.

In US patent US 4 088 199 a tilting vehicle is described where the engine is able to tilt with the driver's section. The driven rear wheel also tilts in concert, so that there is no angle of turn between the transmission, that is formed by a chain, and between the sprocket of the driven rear wheel. Joint tilting of the drive has the advantage that better driving behaviour in the bends can be obtained as a result of the additional tilting weight.

One aim of the invention is to provide a tiltable vehicle wherein the drive device is accommodated in a first, tiltable frame section and wherein the driven wheels are accommodated in the second frame section that remains upright.

A further aim of the invention is to provide a tiltable vehicle wherein the drive device is accommodated in the tiltable frame section, wherein the disruption of tilting by the moment that the drive device exerts on the tiltable frame section is counteracted or prevented.

A further aim of the invention is to provide a tiltable vehicle wherein compact and relatively simple transmission of the drive torque of the drive device to the driven wheel is obtained.

To this end the tilting vehicle according to the invention is characterised in that the first frame section has a drive device with a rotary drive shaft, which is connected via a mechanical coupling to a wheel axle of the at least one wheel of the second frame section, wherein the tilting vehicle is provided with a moment sensor which is coupled to the drive shaft for determining a moment exerted by the drive shaft, and a force generator that, at one end, is mechanically connected to the first frame section and, at the other end, is mechanically connected to the second frame section and that is coupled to the moment sensor for exerting a moment on the second frame section depending on the moment of the drive shaft determined by the moment sensor.

By accommodating the drive device in the tiltable section the advantage of the additional tilting mass is obtained, as a result of which stability in bends is improved and, moreover, greater design freedom is obtained compared with a vehicle layout as given in WO 95/34459.

By measuring the drive torque that is exerted by the engine on the second frame section and compensating for it via the force generator, the disruptive moment that the drive torque causes between the first and the second frame section can be counteracted. This compensation is necessary, both in tilting vehicles that are balanced by the driver and in tilting vehicles with actively/automatically actuated tilting because in the case of motorised tilting vehicles the drive torque can rise to an order of magnitude of 100 - 1000 Nm, which gives an appreciable improvement in the tilting moment.

In one embodiment the mechanical coupling comprises a planetary gear system with a sun gear that is joined to the drive shaft, which sun gear is connected via planet gears to an outer ring that can rotate with respect to the sun gear, which planet gears are joined to an input drive shaft, wherein the sensor is also the force generator and comprises a peripheral gear connected to the outer ring such that it can rotate, which peripheral gear is mechanically connected to the second frame section and wherein one end of the drive shaft is mechanically connected to the wheel axle. As a result compact and robust moment compensation is obtained. Preferably, the drive shaft runs in an essentially straight line in the direction of the tilt axis.

In a further embodiment the tilting vehicle is provided with a moment sensor that is coupled to the drive shaft and a with second drive shaft located concentrically with the drive shaft, which second drive shaft, at one end, is connected via the mechanical coupling to the wheel axle of the at least one wheel of the second frame section and, at the other end, is connected to a second drive device, wherein the moment sensor is connected to the second drive device for controlling the second drive device to rotate the second drive shaft in the opposing direction compared with the first drive shaft, such that the sum of the moments of the first and second drive shafts is relatively small, preferably zero, as a result of which the disruptive effect of the drive moment is eliminated.

This embodiment as well can advantageously be constructed as a planetary gear system, wherein the sun gear is joined to the drive shaft, which sun gear is connected via planet gears, which are coupled to an incoming part of the drive shaft, to an outer ring that can rotate with respect to the sun gear, wherein the moment sensor is also the second drive device and comprises a peripheral gear connected to the outer ring such that it can rotate, which peripheral gear is mechanically connected to the outer drive shaft and drives this outer shaft in rotary movement.

The abovementioned embodiments of the device for moment compensation are in particular advantageous if a drive shaft located in the longitudinal direction is used. This drive shaft is able to follow the tilting movement between the first and second frame section without any problem, but necessitates compensation of the disruptive moment that the drive shaft exerts on the non-tilting frame section.

An alternative solution for transmission of the drive from the tilting to the non-tilting section without a disruptive moment being exerted is the use of a mechanical coupling that is connected to a wheel axle of the at least one wheel on the second frame section, wherein the mechanical coupling comprises a drive gear located transversely to the wheel axle that engages on the wheel axle to rotate the latter, which drive gear is provided with guide means for tilting the drive gear about a drive tilt axis that extends in the direction of the tilt axis in concert with tilting of the first frame section. In this situation the drive moment gives rise to a moment in the transverse direction of the vehicle, where the nose of the vehicle will want to rise or fall. This moment can be absorbed well by the construction and has no adverse effect on tilting.

The drive gear can, for example, be connected to the wheel axle via a homokinetic transmission (constant velocity drive). The drive gear can be a gear or sprocket that is driven, via a toothed belt or chain, by a driven gear located on the tilting frame section, where the plane of the toothed belt or chain path is also tilted during tilting. The drive gear can also be provided with bevel teeth that engage on helical teeth on the drive shaft. The driven wheels can remain vertical as described in WO 95/34459 or can tilt in concert.

hi one embodiment the non-tilting section has two wheels that are connected to one another via a differential. The tiltable drive gear is mounted on a separate shaft. A few embodiments of a tilting vehicle according to the invention will be explained in more detail below with reference to the appended drawing. In the drawing:

Fig. 1 shows a diagrammatic, perspective view of a tilting vehicle according to a first embodiment with moment compensation by force transmission, Fig. 2 shows a perspective view of a first embodiment [lacuna] a planetary gear system for use in the tilting vehicle according to Claim 1, Fig. 3 shows a perspective view of a second embodiment [lacuna] a planetary gear system for use in the tilting vehicle according to Claim 1, Fig. 4 shows a diagrammatic, perspective view of a tilting vehicle according to a second embodiment with moment compensation by use of concentric drive shafts rotating in opposite directions, Fig. 5 and Fig. 6 show, respectively, a perspective view of an embodiment [lacuna] a planetary gear system for use in the tilting vehicle according to Claim 1, and an exposed view thereof, Fig. 7 shows a diagrammatic, perspective view of a tilting vehicle according to a third embodiment with a drive gear that tilts in concert on the driven rear wheel axle, Figs 8 and 9 show a first embodiment of a tilting drive gear on the driven wheel axle, Figs 10 and 11 shows a second embodiment of a tilting drive gear on the driven wheel axle, Fig. 12 shows an embodiment of a tilting drive gear that interacts with a differential transmission in the rear wheel axle, and Fig. 13 shows an embodiment where a differential of the wheel axle of the rear, non-tilting frame section is able to remain horizontal, whilst the driven [lacuna] tilt, and Fig. 14 shows an embodiment with a differential of the wheel axle of the rear frame section that tilts in concert.

Fig. 1 shows a tilting vehicle 1 with a front frame section 2 and a rear frame section 3. The front frame section 1 is joined via a pivot joint to the rear frame section 3 and is able to tilt with respect to the frame section 3 about a tilt axis 5 that extends in the longitudinal direction of the vehicle 1. The front frame section 2 is provided with a front wheel 7 that is connected to the front frame section 2 via a front fork 9 such that it is able to rotate virtually freely about a front wheel steering axis 8. The front wheel 7 is connected via a system of rods 10 to a steering device 11. The angular position of the steering column of the steering device 11 with respect to the front wheel steering axis 8 is transmitted via a mechanical, electrical or hydraulic sensor, which is indicated diagrammatically by the line 13, to the tilt drive 14, which, at one end, is fixed to the rear frame section 3 and, at the other end, to the front frame section 2. In the embodiment shown the tilt drive comprises two hydraulic cylinders 15, 16 that engage on an arm 4 of the front frame section.

The front frame section 2 has a driver's seat 12 that is indicated by a broken line in the figure. The front frame section 2 furthermore has a drive or engine 17, with a drive shaft 18 that extends rearwards in the longitudinal direction of the vehicle. The end of the drive shaft 18 is provided with (conical) teeth 19 that engage on a drive gear 20 that is j oined to the wheel axle 21 of the rear frame section 3. Two rear wheels 22, 23 are joined to the wheel axle 21. A moment sensor 24 that is connected to the engine 17 and/or the drive shaft 18 is also provided. This is indicated diagrammatically by the line 27. Furthermore, the moment sensor is is (sic) mechanically, electrically or hydraulically coupled via a link indicated diagrammatically by a line 26 to a force generator 25, which, at one end, is connected to the front frame section 2 and, at the other end, to the rear frame section 3.

When taking a bend, the driver of the tilting vehicle 1 effects an angle of turn between the steering column of the steering device 11 and the front wheel steering axis 8. This angle of turn is transmitted via a sensor, of which the system of rods 10 forms part, via the transmission 13 to the tilt drive 15, which rotates the front frame section about the tilt axis 5 with respect to the rear frame section 3, which remains upright. As a result of tilting, the front wheel 7 will automatically turn to some extent about front wheel steering axis 8, so that the angular difference with the steering column of the steering device 11 decreases. When a preset difference value between the angular positions of the front wheel 7 and the steering device 11 is reached, driving of the tilting movement is interrupted and the tilt position remains constant, suited to the speed and the radius of the bend. The mode of operation of the system of rods 10 and control of the tilt cylinders 15, 16 is described in detail in WO 99/14099 in the name of the Applicant, which publication is incorporated herein by reference. An alternative method for controlling the tilt cylinders 15, 16 that can also be used is described in WO 95/34459, likewise in the name of the Applicant.

As a result of rotation of the drive shaft 18 a moment is produced on the front frame section 2 that has a disruptive effect on tilting. For example, in the case of active tilting as is described in WO 99/14099 a tilting moment of 1000 Nm can be exerted on the front frame section 2, whilst a torque of 300 Nm can be exerted by the drive shaft on the front frame section 2. Variation of the speed of revolution and torque of the drive shaft 18 have an appreciable effect on the driving behaviour. This adverse effect is compensated by determining the moment of the drive shaft 18 with respect to the front frame section 2 by means of the moment sensor 24. The moment sensor can be a physical sensor, such as a strain gauge that is connected to the drive shaft and that produces tension dependent on the moment. It is also possible that the sensor 24 comprises a computing unit that forms part of an engine management system and that calculates the torque of the drive shaft, or reads it from a look-up table, on the basis of the speed of revolution and fuel consumption. On the basis of the torque determined for the drive shaft, a control signal is formed by the sensor 24 which is transmitted to the force generator 25, which exerts an equal and opposite torque on the front frame section 2. The control signal can be transmitted electrically, mechanically, hydraulically or pneumatically, or by combinations thereof, hi this way the effect of the torque of the drive shaft 18 on tilting of the front frame section can be eliminated.

In Figure 2 an embodiment is shown where the moment sensor 24, the force generator 25 and the link 26 are formed by a planetary gear system with three planet gears 31, 32, 33, which planet gears are joined to the input drive shaft 18'. A sun gear 30 is fixed to the output part 18" of the drive shaft 18. A satellite gear 34 is arranged around the planet gears 31, 32, 33. The planetary gear system 30, 31, 32, 33, 34 can be accommodated in a housing - not shown in the figure - that is firmly fixed to the front frame section 2. A peripheral gear 35 is connected to the outer teeth of the satellite gear 34 (alternatively, the peripheral gear can also engage via friction on a non-understood (sic) outer periphery of the satellite gear 34) and drives a set of rods 36, 37. The rod 37 is connected to the rear frame section 3. In the embodiment shown, if no tilting of the front frame section 2 takes place the satellite gear 34 will be stationary. The moment of the input shaft 18' is then distributed in accordance with a fixed ratio over the satellite gear 34 and the sun gear 30 joined to the output drive shaft 18". This ratio of the moments that are effective on the satellite gear 34 and on the output drive shaft 18" is dependent on the gear ratio between the inside of the satellite gear 34 and the sun gear 30. The rotational velocities of the satellite gear 34 and of the output shaft 18" can vary. By setting the correct length of the arm 37, a moment is exerted on the rear frame section 3 by the peripheral gear 35 that is equal in magnitude and opposite to the moment that is exerted by the output drive shaft 18" on the rear frame section 3.

If the front frame section 2 is tilted, the satellite gear 34 will rotate relative to the rear frame section 3, whilst the moment exerted by the peripheral gear 35 and the lever 37 on the rear frame section remains the same as the moment that is exerted by the drive shaft 18" on the rear frame section 3, so that tilting of the front frame section is not influenced by the rotation of the drive shaft 18.

In Figure 3 an embodiment is shown that is similar to the embodiment according to Figure 2 and where the input drive shaft 18' is once again joined to the planet gears 30-32 and the output drive shaft 18" is joined to the sun gear 30. The peripheral gear 35 is connected via a gear 38 and a chain 39 to a gear 43 that is firmly joined to the rear frame section 3. By choosing the correct transmission ratio between the teeth of the peripheral gear 35 and of gears 38 and 43, the moment exerted by the peripheral gear 35 on the rear frame section 3 can be made equal (and opposite) to the moment exerted thereon by the output drive shaft 18".

In the embodiment that is shown in Figure 4 an inner drive shaft 18 and an outer drive shaft 40 are installed between the drive device 17 on the tiltable frame section 2 and the rear wheel axles 21, 21' on the rear frame section 3 that remains upright. A moment sensor 41 is connected via a line 27, indicated diagrammatically, to the inner drive shaft 18, to the drive device 17 or to another component of the drive of the tilting vehicle (for example to an on¬ board computer for engine management that derives the torque from the speed of revolution and the fuel consumption) for determining a moment that is exerted by the drive shaft 18. The moment sensor 41 is coupled to a second drive device 42, which drives the outer drive shaft 40 with a moment that is equal to the moment of the inner drive shaft 18 but in the opposite direction, so that no net moment is exerted by the joint drive shafts 18 and 40 on the rear frame section 3. The second drive device 42 can be a separate motor, or can comprise a mechanical coupling to the drive device 17. Each drive shaft 18, 40 is connected to a respective rear wheel axle 20, 21' via a separate drive gear 20, 20'. The moment sensor 41 and the second drive device 42 according to Figure 4 are shown in detail in Figure 5. The moment sensor 41 comprises a planetary gear system with a sun gear 30 that is fixed to the output, inner drive shaft 18", planet gears 30, 31, 32 (sic) that are fixed to the input drive shaft 18' of the drive device 17 and satellite gear 34, as well as a peripheral gear 35. The satellite gear 34 rotates at the same angular velocity as the sun gear 30 and drives the peripheral gear 35. Ih this case the planet gears act as a rigid link between the sun gear 35 (sic) and the peripheral (sic) gear 34. The second drive device 42 comprises a link gear 45, a drive gear 47 joined to the outer drive shaft 40 and a drive belt 46. The outer drive shaft 40 is provided at its end with a gear 48 that engages on bevel teeth of the drive dish 20 for rear wheel axle 21. At its end the drive shaft 18" has a gear 19 that engages on bevel teeth of the drive dish 20' for rear wheel axle 21'. The transmission ratio of the gear 48 and the drive dish 20 is the same as the transmission ratio of the gear 19 and the drive dish 21', so that the axles 21 and 21' are rotated with the same torque in the same circumferential direction.

The exposed construction of the planetary gear system according to Figure 5 is shown in Figure 6, where the directions of rotation are indicated by arrows. The connection between the input drive shaft 18' and the planet gears 31-33 via a flange 50 on the drive shaft and connecting pins 51 , around which the gear wheels of the planet gears are mounted on bearings such that they can rotate, can clearly be seen.

Figure 7 shows a tilting vehicle where a drive member 55 is incorporated that is joined to the rear wheel axle 21 and that is able to tilt in concert with the front frame section 2 about an axis 54 running parallel to the tilt axis 5. The drive member can comprise, for example, a homokinetic coupling (constant velocity drive) known per se, on the housing of which teeth are incorporated on which the drive shaft 18 engages via teeth or via a chain or drive belt. Tilting of the drive member can be effected via a mechanical link 56, such as a rod, to the tiltable frame section 2 or can be effected via a separate force generator or via the drive shaft 18.

In Figure (sic) 8 and 9 a first embodiment of the tiltable drive member 55 is shown, where the rear wheel axle 21 is provided with a guide member 56 with a number of grooves 57 running in the axle direction, into which internal teeth 58 of the drive gear 59 drop. Bevel teeth 60 at the periphery of the drive gear 59 engage on the teeth 19 of the drive shaft 18. When the front frame section 2 tilts, the drive shaft transmits the tilting moment to the drive gear 59, as a result of which this tilts into the position as shown in Figure 9 and the drive moment of the axle 18 is again transmitted in the same way to the drive gear 59 as in Figure 8, without this disrupting tilting of the front frame section.

A second embodiment of the tiltable drive member 59 is shown in Figure (sic) 10 and 11, where a drive gear 66 is provided that engages via internal teeth 67 on the longitudinal grooves in the guide member 56 and where the a (sic) radial teeth 68 on the periphery of the drive gear 66 interact with a drive belt 69 that is driven by the pinion 65 of the drive shaft 18 at right angles.

As stated, the guide member 56 is indicated diagrammatically and this can be implemented, for example, by a homokinetic transmission, the housing of which is firmly joined to the drive gear 59, 66.

A combination of a tiltable drive member 55 according to Figure (sic) 8 and 9, that drives a differential 72 via an intermediate shaft 70, a sprocket 71 and chain 73, is shown diagrammatically in Figure 12. Two separate rear wheel axles 20, 21' can be driven with equal moments and different speeds of revolution by the differential 72 of a type known per se. The advantage of this construction is that additional space is obtained to accommodate the differential 72, so that this does not have to be integrated with the (homokinetic) drive member 55, which is highly complex from the structural standpoint.

Figure 13 shows a preferred embodiment where the wheels 22 and 23 of the rear frame section 3 are able to tilt in concert with the front frame section 2. The differential 72 remains virtually horizontal as a result of the use of the moment compensation according to the invention. A pivot joint (homokinetic) 76, 77 is incorporated in each rear wheel axle 21, 21', which pivot joints join axle sections 73, 74 of rear wheel axle 21 and axle sections 73' and 75 of rear wheel axle 21' to one another. In the embodiment with tilting rear wheels 22, 23 according to Figure 14 where (sic) the differential 72 tilts in concert with the front frame section. Additional hinge points 83 and 84 are incorporated close to the differential 72 in the rear wheel axles 21, 21', the disadvantage being that the change in length in the axles in the transverse direction is relatively large.

Although a vehicle with a tiltable front wheel and two rear wheels that remain upright has been shown in the embodiment shown above, the invention is also applicable to tiltable vehicles with a single front wheel and a single rear wheel, with two front wheels and a single rear wheel or with two front wheels and two rear wheels. Furthermore, in the embodiments shown tilting of the tilting vehicle is actively driven, but the invention is also applicable to vehicles where tilting is partially or completely effected by the weight and/or the muscle power of the driver.