GB1591568A

GB1591568A - Vehicle reversing apparatus

Info

Publication number: GB1591568A
Application number: GB2457778A
Authority: GB
Original assignee: COLLIN CONSULT LARS AB
Current assignee: COLLIN CONSULT LARS AB
Priority date: 1978-05-30
Filing date: 1978-05-30
Publication date: 1981-06-24

Description

(54) VEHICLE REVERSING APPARATUS (71) We, LARS COLLIN CONSULT AB., a Swedish Company of Vasterbergsgatan 3, 431 39 Molndal, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to vehicles, primarily heavy motor vehicles such as trains, heavy goods vehicles, military vehicles, both wheeled and tracked, and earth moving equipment.

The invention is concerned with propulsion plant for such vehicles and apparatus whereby reverse drive may be achieved.

When designing high output propulsion machinery reversing has hitherto been a limiting factor. Certain types of prime movers are designed to be directly reversible so they can supply the required output in both directions of rotation. Other machinery such as for instance turbines, do not possess such properties, while, with a third type, reversing being possible, constructional and operational complications make it more convenient to reverse by means other than the power unit itself.

Reversible gears have been proposed, where the torque is transferred to different combinations of gears by means of hydraulic clutches being filled and emptied and in turn connecting the machinery to the output to the ground engaging elements, through different gear trains.

It has also beeri proposed, during a reversing operation, to reduce the torque acting upon the gear approximately to zero, by means of brakes mounted on a drive shaft.

As long as the vehicle is moving the drive shaft must be braked and this imposes a heavy load upon the brake.

In Patent Specification No. 1,446,920 there is described and claimed a marine propulsion plant including a gas turbine with a work turbine mounted on a shaft and a reversing gear comprising a first part mechanically connected to the work turbine, a second part connected to a propeller shaft, means for maintaining said parts in either of two working positions, means for governing the flow of motive fluid to the turbine, brake means for braking the work turbine and mounted on the work turbine shaft and the part of the reversing gear connected thereto, bearing means for the turbine rotor permitting rotation thereof in two opposite directions, and means on the reversing gear permitting transfer of torque from the work turbine shaft to the propeller shaft as well as in the opposite direction.

It is the object of this invention to profide a modification of this plant, with reversing facilities, in a convenient form for ground engaging vehicles.

According to the invention there is provided a propulsion plant in a vehicle having ground engaging elements, said plant including a gas turbine including a work turbine mounted on a shaft and a reversing gear comprising a first part mechanically connected to the work turbine, a second part connected to a drive shaft to the ground engaging elements, the work turbine and parts rotatable therewith having significantly less inertia than the drive shaft and parts rotatable therewith, means for maintaining said parts in either of two working positions, means for governing the flow of motive fluid to the turbine, brake means acting on the work turbine shaft to brake said shaft and the part of the reversing gear connected thereto, bearing means for the turbine rotor permitting rotation thereof in two opposite directions, and means on the reversing gear permitting transfer of torque from the work turbine shaft to the drive shaft as well as in the opposite direction.

Since the parts of the reversing gear have low inertia, it will be comparatively easy to brake the turbine after removing the supply of motive fluid thereto, and then to re-engage the gear parts. The turbine will then be forced to rotate "backwards" by the inertia of the drive shaft, but the latter will first be braked and then caused to rotate in the new direction, when motive fluid is re-applied to the turbine.

Figure 1 shows schematically a propulsion plant for a vehicle having ground engaging elements, said plant including a gas turbine and reversing gear, Figures 2-5 show, still more schematically, the relative rotating directions of the components of the gear during various steps in a reversing operation, Figure 6 shows a further embodiment of a vehicle propulsion plant constructed according to the invention, Figure 7 is a section through a portion of the nozzle and blade system of the gas turbine, Figure 8 shows, very schematically, the design of a reversible epicycling gear, and Figure 9 shows a detail of the clutch means in a preferred embodiment of the reversing gear.

The propulsion plant illustrated in Figure 1 is for a heavy vehicle having ground engaging elements which may be wheels or tracks. The plant shown comprises a gas generating portion including a compressor 10, a combustion chamber 11 and a first turbine 12 driving the compressor. The combustion chamber is provided with a burner 13 having means 14 for governing the generation of motive fluid to the main, or propulsion work turbine 15.

This is shown as a single stage unit, but it is evident that, depending upon the power to be generated and other well known factors determining the general layout of the plant, several expansion stages may be provided, and that more than one gas generating unit may be included in the plant.

The work turbine is carried in bearings 16, which, contrary to the design common with known gas turbines, are arranged in a manner to permit the turbine to rotate in opposite directions.

The turbine 15 drives, by means of a reversing gear, the function of which is to be described below, a drive shaft 17, to the end of which a differential 18 is mounted. The final drive arrangements are however dependant upon the type of vehicle to which the propulsion plant is fitted. Depending upon the size of the vehicle the drive shaft may be composed of a number of interconnected lengths of shafting.

A big gear 19 is fitted to the forward end of the shaft 17. Two pinions 20 and 21 mesh with this big wheel, and each of said pinions is connected to one half-portion 22 and 23, respectively, of slipping type clutch means.

The other two half-portions 24 and 25 of said clutch means are connected to the two intermeshing pinions 26 and 27, the former, as well as the associated half-portion 24 of the clutch, being mounted upon the output shaft 28 of the turbine 15.

A brake 29 is fitted to the forward end of the turbine shaft 28.

Clutch portions 24, 22 co-operate for one direction of rotation of the drive shaft 17 and clutch portions 25, 23 co-operate for the opposite direction of rotation. Both clutches may be disengaged simultaneously, leaving the turbine part completely free of the drive shaft.

Figure 1 indicates an engagement of clutch portions 24 and 22, which means that elements 26, 24, 22, 20, 21 and 23 rotate in the same direction, whereas elements 27 and 25 rotate in the opposite direction.

It should be noted that clutch portions 25 and 23 rotate in opposite directions, and it is evident that reversing of the rotation of the drive shaft cannot simply be brought about by disengaging clutch 24, 22 and engaging clutch 25, 23.

The main steps involved in a reversing operation are schematically illustrated in Figures 2 to 5. First of all the supply of motive fluid to the work turbine 15 is cut off, and thereafter the clutch 24, 22 is disengaged.

The movement of the vehicle will continue, and the momentum will continue to drive the drive shaft 17 and the part of the gear mechanically connected thereto, in the same direction as before.

The inertia of the turbine 15 and the part of the gear mechanically connected thereto will also make these parts continue to rotate in the same direction as before, but no power is supplied thereto, so the speed will be rapidly reduced.

As shown in Figure 3 the brake is then applied and the turbine 15 is brought to a stand still, or almost so.

It will now, as shown in Figure 4, be possible gradually to engage clutch 25, 23.

The drive shaft system is still rotating in the original direction, and the engagement of the second clutch will cause the turbine part of the gear to rotate "backwards". This imposes a load on the drive shaft, which reduces its tendency to rotate.

When the second clutch is fully engaged, motive fluid is supplied to the work turbine 15, which now be rotating contrary to its normal working direction. The action of the motive fluid upon the rotor blades will first fully brake the now interconnected system from the turbine 15 to the shaft 17 and finally cause the shaft 17 to rotate in the new direction of rotation.

The braking of the turbine section of the system separate from the drive shaft will be greatly enhanced due to the fact that it is possible to design the turbine section in such a manner that the inertia thereof will be considerably less than that of the drive shaft section of the system. Even if the turbine 15 rotates at much higher speed than the drive shaft, the weight and size of the elements of the turbine section are markedly less than those of the drive shaft section.

The propulsion plant shown in Figure 6 includes the same basic components as the one of Figure 1, and like components are denoted by the same legends. Thus there are the compressor 10, the combustion chamber 11 and the compressor turbine 12, as well as the burner 13 and its control means, which form a motive fluid generating unit. The main work turbine 15 is connected to the drive shaft 17 by means of a reversible epicyclic gear 30, to be described better below in connection with Figure 8. A motor for starting the gas generating unit is denoted by 31.

The braking of the main work turbine 15 is here brought about partly by means of a hydraulic device including a machine 32 of the well known swash plate type, which can operate either as a pump or as a motor, and is driven by the turbine by way of a gear train 33. The inclination of the swash plate is determined by means of a control device 34 of well known type.

The hydraulic machine is connected to a reservoir 35 for hydraulic fluid. as well as to a pressure storage tank 36.

The hydraulic machine 32 is normally maintained in a neutral position. in which it performs no work and consumes very little energy. If there is a need for hydraulic pressure fluid within the power plant in general, the machine may of course be used to supply such fluid. Concern here however.

is with the braking activity and such possibility will be disregarded.

During a reversing operation, and corresponding to the step illustrated in Figure 3.

the swash plate of the machine will be brought to a position turning the machine into a pump. This will draw fluid from the reservoir 35 and force it into the storage tank 36. The braking effect of the machine will cease when the counterpressure in the tank reaches a certain level, which, to some extent, will be determined by the capacity of the tank. It will be evident from the following description of the reversing gear 30, that positive braking effect is also attainable therethrough.

The pressure fluid stored in the tank 36 may be used to aid the rotation of the turbine. The swash-plate of the machine 32 is then brought to a position turning the machine into a motor.

This may be switched in just before the step illustrated in Figure 4. this is just when the turbine has been brought to a stand-still.

to start the turbine in its backwards rotation before clutch 25,, 23 is being engaged. if both clutch halves rotate in the same direction.

although at different speed the shock will be less than if one part is stationary. The motor may however also be switched in when the clutch if fully engaged in order to aid the turbine in braking the drive shaft.

Certain types ofgas generator units cannot be completely shut down. but must continue to generate some amount of gas. In order to prevent motive fluid being supplied to the main work turbine 15 during the braking step, a bleed-ott valve 37 is provided. b! means of which any desired amount of motive fluid may be made to by-pass the work turbine.

Even if the reversing gear is of a type different from that in Figure 1 the steps involved in the braking operation are basically the same.

The fact that the turbine for a short tine will be rotated "backwards" greatly enhances its braking effect, as will appear in Figure 7.

The inlet guide vanes are denoted by 38 and the turbine blades by 39.

The absolute inlet speed of the motive fluid is denoted by a and the relative speed of the rotor by u. This means that the relative speed and direction of the fluid entering the rotor blades will have the magnitude denoted by b.

When the rotor is rotated 'backwards".

with approximately the same speed. the relative speed and direction of the Huid will correspond to c. which may be as much is twice the amount of a. With the gas generator operating at full output and by governing the supply of motive fluid to the main work turbine by means of the bleed-off valve 37 this braking effect be brought up from zero to full magnitude in a short interval of time.

As a gear. any reversible reduction gear is used. For large outputs the epicyclic gear has proven very useful. as it provides a high degree of reduction with comparatively small space requirements. Such a gear is schematically shown in Figure X.

A first sun gear 40 is mounted upon the turbine shaft 28 and a first rim wheel 41 is rotatably mounted thereon. This rim wheel carries a first set of planetary gears 42.

meshing with the sun gear 40.

A second rim wheel 43 is rotatably mounted upon the drive shaft at the end of which a planetary carrier 44 is fitted. The second rim wheel 43 is provided with one externally toothed gear 45 serving as a sun gear for a second set of planetary gears 4h carried by the planetary carrier 44, as well as with an internally toothed gear ring 47 cooperating with the first set of planetary gears 42. A planetary carrier 48 having an internally toothed gear ring 49 for co-operating with the second set of planetary gears 46 is carried by the first rim wheel 41 by means of the shafts of the first planetary gears 42.

Either of the two rim wheels may be kept stationary by means of locking devices 50 and 51, respectively. These may be of any well known type, but are here preferably also designed in such a manner that they may exert a braking effect upon the associated rim wheel. It is evident that when both locking devices are released, the turbine and the drive shaft lack any torque transferring connection.

The function of the gear is as follows.

Suppose first that rim wheel 41 is locked. The rotation of sun gear 40 is then, by way of the first planetary gears 42, transferred to the second rim wheel 43 by way of its internally toothed gear ring 47. The rotation of the second rim wheel is transferred to the drive shaft 17 by way of the externally toothed gear 45 thereon, the second planetary gears 46 and the planetary carrier 44, the internally toothed gear ring 49 being kept stationary by the first rim wheel 41.

If instead, the second rim wheel 43 is locked, the power is transferred from the first sun gear 40 by way of the first planetary gears 42 to the internally toothed gear ring 49-internally toothed gear ring 47 being stationary. The internally toothed gear ring 49 directly co-operates with the second set of planetary gears 46, and as also the external gear 45 is stationary the torque is transferred directly to the planetary carrier 44.

A reversing gear of the above described type has noted advantages with respect to requirements for space. With respect to the braking properties it is, as above mentioned, of importance that the part of the gear connected to the turbine be as small as possible. If that point is of major importance a gear of the type shown in Figure 9 may be used.

The gear will basically be of the same type as the one shown in Figure 1, i.e. there is a big gear 55 fitted to the end of the drive shaft 17 and there are two pinions 56 and 57 engaging the same. Two meshing gears 58 and 59 are provided at the side of the big gear 55 remote from the work turbine 15.

The gear 59 is directly connected to the pinion 57, but there is no direct mechanical connection between the gear 58 and the pinion 56.

The shaft 28 of the work turbine 15 is provided with a brake 29 and is continued by a quill shaft 60 passing through the pinion 56 and the gear 58. Intermediate these last mentioned elements there is a clutch device 61, of known type, which by means of a governing device 62 may be kept in a neutral position, disengaging both elements, or which may connect the quill shaft to any of them.

It is evident, that the rotating parts following the turbine during full disengagement of the clutch wil be very small, and that the gear will operate in the same basic manner as described in connection with Figure 1.

WHAT WE CLAIM IS: 1. A propulsion plant in a vehicle having ground engaging elements, said plant including a gas turbine including a work turbine mounted on a shaft and a reversing gear comprising a first part mechanically connected to the work turbine, a second part connected to a drive shaft to the ground engaging elements, the work turbine and parts rotatable therewith having significantly less inertia than the drive shaft and parts rotatable therewith, means for maintaining said parts in either of two working positions, means for governing the flow of motive fluid to the turbine, brake means acting on the work turbine shaft to brake said shaft and the part of the reversing gear connected thereto, bearing means for the turbine rotor permitting rotation thereof in two opposite directions, and means on the reversing gear permitting transfer of torque from the work turbine shaft to the drive shaft as well as in the opposite direction.

2. A vehicle propulsion plant according to claim 1 in which the means for governing the flow of motive fluid to the work turbine includes a bleed-off valve means.

3. A vehicle propulsion plant according to claim 1 or claim 2 in which the brake means is a mechanical brake directly connected to the work turbine shaft.

4. A vehicle propulsion plant according to claim 1 or claim 2 in which the brake means includes a hydraulic machine operable as a pump or as a motor, means for drivingly connecting said machine to the work turbine and a pressure tank operatively connected to the said machine.

5. A vehicle propulsion plant according to any one of the preceding claims, in which the reversible gear is an epicyclic gear having two rim wheels as well as brake means at each of said rim wheels for keeping either of them in a locked position.

6. A vehicle propulsion plant as claimed in claim 1, in which said reversing gear includes a first gear rotatable with the drive shaft, a second and a third gear meshing with the first gear, intermeshing fourth and fifth gears, said fourth gear being aligned with the second gear, but mechanically separated therefrom and said fifth gear being aligned with the third gear and mechanically connected thereto, a through bore in the second gear permitting the passage of the end of the work turbine shaft, a two-part clutch means intermediate said second and fourth gears, a first part of said clutch means being mechanically connected to the said end of the drive shaft, means for axially displacing the second,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. carried by the first rim wheel 41 by means of the shafts of the first planetary gears 42. Either of the two rim wheels may be kept stationary by means of locking devices 50 and 51, respectively. These may be of any well known type, but are here preferably also designed in such a manner that they may exert a braking effect upon the associated rim wheel. It is evident that when both locking devices are released, the turbine and the drive shaft lack any torque transferring connection. The function of the gear is as follows. Suppose first that rim wheel 41 is locked. The rotation of sun gear 40 is then, by way of the first planetary gears 42, transferred to the second rim wheel 43 by way of its internally toothed gear ring 47. The rotation of the second rim wheel is transferred to the drive shaft 17 by way of the externally toothed gear 45 thereon, the second planetary gears 46 and the planetary carrier 44, the internally toothed gear ring 49 being kept stationary by the first rim wheel 41. If instead, the second rim wheel 43 is locked, the power is transferred from the first sun gear 40 by way of the first planetary gears 42 to the internally toothed gear ring 49-internally toothed gear ring 47 being stationary. The internally toothed gear ring 49 directly co-operates with the second set of planetary gears 46, and as also the external gear 45 is stationary the torque is transferred directly to the planetary carrier 44. A reversing gear of the above described type has noted advantages with respect to requirements for space. With respect to the braking properties it is, as above mentioned, of importance that the part of the gear connected to the turbine be as small as possible. If that point is of major importance a gear of the type shown in Figure 9 may be used. The gear will basically be of the same type as the one shown in Figure 1, i.e. there is a big gear 55 fitted to the end of the drive shaft 17 and there are two pinions 56 and 57 engaging the same. Two meshing gears 58 and 59 are provided at the side of the big gear 55 remote from the work turbine 15. The gear 59 is directly connected to the pinion 57, but there is no direct mechanical connection between the gear 58 and the pinion 56. The shaft 28 of the work turbine 15 is provided with a brake 29 and is continued by a quill shaft 60 passing through the pinion 56 and the gear 58. Intermediate these last mentioned elements there is a clutch device 61, of known type, which by means of a governing device 62 may be kept in a neutral position, disengaging both elements, or which may connect the quill shaft to any of them. It is evident, that the rotating parts following the turbine during full disengagement of the clutch wil be very small, and that the gear will operate in the same basic manner as described in connection with Figure 1. WHAT WE CLAIM IS:

1. A propulsion plant in a vehicle having ground engaging elements, said plant including a gas turbine including a work turbine mounted on a shaft and a reversing gear comprising a first part mechanically connected to the work turbine, a second part connected to a drive shaft to the ground engaging elements, the work turbine and parts rotatable therewith having significantly less inertia than the drive shaft and parts rotatable therewith, means for maintaining said parts in either of two working positions, means for governing the flow of motive fluid to the turbine, brake means acting on the work turbine shaft to brake said shaft and the part of the reversing gear connected thereto, bearing means for the turbine rotor permitting rotation thereof in two opposite directions, and means on the reversing gear permitting transfer of torque from the work turbine shaft to the drive shaft as well as in the opposite direction.

part of the said clutch means into engagement with either of said second or fourth gears.

7. A method for reversing the drive shaft of a power plant in a vehicle having ground engaging elements, said plant including a gas turbine including a work turbine mounted on a shaft and a reversing gear comprising a first part. mechanically connected to the work turbine, a second part connected to a drive shaft to the ground engaging elements, the work turbine and parts rotatable therewith having significantly less inertia than the drive shaft and parts rotatable therewith, brake means on the work turbine shaft, and means to maintain said parts in either of two different working positions, the method comprising the steps of cutting off the supply of motive fluid to the turbine, disengaging the first and the second parts of the reversing gear from each other while in one of said working positions and operating said brake means to brake the first mentioned part, engaging the parts of the reversing gear in their other working position, thereby momentarily permitting the first part to rotate the work turbine in a direction contrary to its normal running direction, and providing successively increasing supply of motive fluid to the turbine to brake the reversing gear and then cause it to rotate in the opposite direction so that the drive shaft rotates in the reverse direction.

8. A vehicle propulsion plant substantially as hereinbefore described with reference to and as shown in Figures 1 to 5 of the accompanying drawings.

9. A vehicle propulsion plant substantially as hereinbefore described with reference to and as shown in Figure 6 of the accompanying drawings.

10. A vehicle propulsion plant substantially as hereinbefore described with reference to and as shown in Figure 8 of the accompanying drawings.

11. A vehicle propulsion plant substantially as hereinbefore described with reference to and as shown in Figure 9 of the accompanying drawings.

12. A method for reversing the drive shaft of a vehicle power plant substantially as hereinbefore described with reference to and as shown in the accompanying drawings.