GB2076757A

GB2076757A - Power and Transmission System for A Vehicle

Info

Publication number: GB2076757A
Application number: GB8109625A
Authority: GB
Original assignee: Noel Penny Turbines Ltd
Current assignee: Noel Penny Turbines Ltd
Priority date: 1980-04-03
Filing date: 1981-03-27
Publication date: 1981-12-09

Abstract

A vehicle power and transmission system of the kind including a prime mover (for example a gas turbine unit 30-37), an electrical generator (45) driven by the primer mover and providing a d.c. output, a battery (52) providing an alternative d.c. output and at least one d.c. motor (50) operable to drive wheels (60) of the vehicle and receiving either one of said d.c. outputs. The system further includes a first control (48) connected to control the operation of the motor or motors (50); a switching device (49) operable to control the application of at least one of the d.c. outputs to the motor or motors (50) through the first control (48); a second control (21, 54) operable to control the prime mover; a third control (55, 57, 58) operable to control the motion of the vehicle, and a microprocessor (47) connected to operate at least one of any of the switching device (49) and the first, second and third controls in response to input signals receivable from driver-operable controls (59, 54, 55) of the vehicle, first sensors (1, 2) responsive to prime mover operational functions and second sensors (6, 7, 8) responsive to vehicle operational functions and to memory and logic devices (53). <IMAGE>

Description

SPECIFICATION Power and Transmission System for a Vehicle The invention relates to a power and transmission system for a vehicle and is particularly, but not exclusively, concerned with such a system for a land vehicle having at least one driven ground-engaging wheel or equivalent endless track-laying device.

An object of the invention is to provide a vehicle power and transmission system including a prime mover having a low specific fuel consumption and an inegrated transmission system which is controllable and which can control the prime mover in a manner such that the fuel is used in optimum economical manner.

According to the invention, a vehicle power and transmission system comprises a prime mover; an electrical generator driven by the prime mover and from which a d.c. output is derived; a battery providing an alternative d.c. output; at least one d.c. motor operable to drive tractionproducing means of the vehicle and receiving either one of said d.c. outputs; first control means connected to control the operation of said motor; switching means operable to control the application of at least one of said d.c. outputs to said motor through said first control means; second control means operable to control the prime mover; third control means operable to control the motion of the vehicle; microprocessor means connected to operate at least one of any of said switching means and said first, second and third control means; means providing signals derived from a plurality of driver-operable controls of the vehicle; first sensors responsive to prime mover operational function; second sensors responsive to vehicle operational functions, and memory and logic devices associated with said microprocessor means, said microprocessor means being operable in response to input signals receivable from said means providing said derived signals, said first and second sensors and said memory and logic devices.

The system may be for a motor vehicle in which said traction producing means comprises driven ground-eng'aging wheels or equivalent endless track-laying devices, and may have at least one said motor arranged to drive at least one pair of said ground-engaging wheels or said endless track-laying devices.

Preferably the electric generator is an alternator of the rotating field type arranged to be driven by the prime mover and the system also includes rectifier means connected to receive an a.c. output from the alternator and to provide the aforesaid d.c. output for said motor or motors.

The alternator may be of a high speed multiphase type.

The rectifier means may comprise one or more semiconductor rectifiers.

The prime mover is preferably a gas turbine power unit.

The gas turbine power unit may comprise twinspool low and high pressure compressor and turbine assemblies, an intercooler between the low and high pressure compressors and a combustion chamber upstream of the high pressure turbine.

a heat exchanger may be provided between the working fluid inlet to the combustion chamber and the exhaust from the low pressure turbine.

Valve means may be provided to control fluid flow through respective heat exchange paths, the valve means being one of said second control means operable by said microprocessor means.

The intercooler may have a downstream ejector pipe into which exhaust gases from the low pressure turbine are arranged to be discharged, thereby to draw air through the intercooler by ejector action.

The or each motor may be of a disc type. There may be a pair or two pairs of driven groundengaging wheels or a pair of equivalent endless track-laying devices, each of said driven groundengaging wheels or a driven member of each of said equivalent devices having a disc type motor mounted directly on a drive shaft thereof.

By way of example a power and transmission system for a road or an off-highway vehicle is now described with reference to the accompanying diagram.

The system comprises as the prime mover a twin spool gas turbine unit of which the low pressure spool drives a multiphase (for example a 3-phase) high speed alternator of which the a.c.

output is rectified and is applied to at least one d.c. motor which drives ground-engaging wheels or equivalent endless track-laying devices of the vehicle.

The prime mover comprises a shaft 30 on which is mounted a low pressure radial flow compressor and a low pressure radial flow turbine rotor 33 directly coupled to drive the compressor rotor 32 by the shaft 30. An axial air inlet to the low pressure compressor 32 draws in air at 61 and this is discharged peripherally from the low pressure compressor rotor 32 into an intercooler 36 through which ambient cooling air is drawn.

Cooled air from the intercooler 36 passes to the inlet of a high pressure compressor rotor 34 which is mounted integrally on a shaft 31 with a high pressure turbine rotor 35 driving the high pressure compressor rotor 34 directly by the shaft 31. Air discharged by the high pressure compressor passes to a combustion chamber 37 supplied with fuel by a fuel pump 38. Hot gases from the combustion chamber 37 pass to the high pressure turbine and this discharges into the low pressure turbine rotor 33. Exhaust gases from the low pressure turbine rotor 33 are introduced through an exhaust pipe 39 directed downstream into an ejector pipe 40 positioned downstream of the intercooler 36.

The velocity in the downstream direction of the exhaust gases issuing from the exhaust pipe 39 draws cooling air through the intercooler 36 by ejector action in the ejector pipe 40. A heat exchanger 41 is shown included in the gas turbine circuit. This is optional but is desirable under low power demand conditions and may not be required where higher power outputs are demanded. Therefore the heat exchanger 41 is provided with infinitely-variable valves 42 and 43 which are operable to bring the heat exchanger into and out of circuit as required. The valve 42 connects the colder fluid path through the heat exchanger between the high pressure compressor 34 and the combustion chamber 37 and the valve 43 connects the higher temperature fluid path through the heat exchanger between the exhaust from the low pressure turbine rotor 33 and the exhaust pipe 39.A suitable heat exchanger having controllable flap valves is described and claimed in British Patent No. 1439661, although those valves are of an "on/off" type instead of being infinitely-variable as required here.

Tha gas turbine cycle is designed to operate at a high turbine entry temperature. The high pressure rotatable assembly comprising the shaft 31 and rotors 34 and 35 may therefore be an integral ceramic structure. The shaft 30 and the low pressure compressor and turbine rotors 32 and 33 may also be an integral ceramic construction.

The alternator 45 is of a high speed type and has a shaft 44 on which the low pressure spool is mounted. Conveniently the shaft 44 and the shaft 30 of the low pressure spool are the same shaft or are integral, there being no gear drive between the shaft 30 and the shaft 44. Thus the rotor of the alternator 45 is driven at the speed of the low pressure shaft 30. The alternator 45 may be of any multiphase type and is shown here as a threephase alternator. The alternator 45 has a rotating magnetic circuit surrounded by stationary inductive windings and there are no slip rings or other sliding electrical contacts between the stator windings and the rotating magnetic circuit or its drive shaft 44. It is envisaged that the rotor of the alternator 45 and the shafts 30 and 44 can be an integral ceramic structure, the rotor of the alternator having magnetic conductors formed in the ceramic.

The a.c. output from the alternator 45 passes to a rectifier 46 which may be of the semiconductor type. The rectifier 46 is part of a "box" 47 illustrated in the diagram and called hereinafter a power management system. The power management system 47 also contains a controller 48 and a switching module 49 which together control the supply of the d.c. output from the rectifier 46 and/or a battery 52 to one, two or four motors 50 which (except where there is only one motor 50) are mounted directly on the shafts of ground-engaging wheels 60, or equivalent endless track-laying devices of the vehicle. Where there is only one motor 50, this would drive a pair of laterally opposite wheels 60 through a conventionai differential drive.Where there are two motors 50, there would be one motor 50 mounted directly on the shaft of each of a laterally-opposite pair of ground-engaging wheels 60. Desirably there are four motors 50 each directly mounted on the shaft of a respective independently suspended ground-engaging wheel 60 of the vehicie, as illustrated. The motors 50 may be of a flat disc construction. The output from the controller 48 to each motor 50 is through further individual control modules 51 in power management system 47. The control modules 51 monitor the torque/speed parameters of the motors 50 and adjust power input to each motor 50 via the controller 48 to balance power contribution of the motors 50 and thus to prevent skidding of the wheels 60. Power management system 47 also includes a memory and logic circuitry illustrated by the box 53.The power management system 47 is of a microprocessor type and controls the switching module 49 and the controller 48 in response to a plurality of driver-operable controls of the vehicle and the prime mover and operational conditions of the vehicle and prime mover and also in response to pre-programmed conditions in the memory and logic box 53.

In the system illustrated power management system 47 has the following input signals: 1. High pressure turbine entry temperature.

2. Rotational speed of the low pressure shaft 30 and hence of the alternator 45.

3. The degree and rate of opening a driveroperable control admitting fuel to the combustion chamber 37. This is conveniently an acceleration demand pedal 54.

4. The degree and rate of operation of a driveroperable tractive effort reduction member. This is conveniently a brake pedal 55.

5. Signals internally of the power management system 47 from the control modules 51 which are responsive to the return signals from the respective wheel motors 50 and so detect the individual acceleration or deceleration of the wheel motors 50.

6. The road speed of the vehicle as determined by a sensor 56 responsive to the speed of rotation of the shaft of one or more of the driven wheels 60.

7. An inertia-responsive device 57, for example, incorporating an accelerometer device, depending on the rate of change of velocity of the vehicle.

8. A signal responsive to the motion of the vehicle limited to particular pre-programmed duty cycle 58 as determined by the memory and logic box 53. This may also include a guidance signal for the vehicle derived from conductors fixed in or adjacent a particular carriageway or in response to the proximity of adjacent vehicles or fixed objects.

9. The phase of the alternator 45 at any instant.

10. The condition of the battery 52.

11. The position of a forward and reverse selector member 59.

In the system illustrated, the power management system 47 also provides the following output signals.

21. A signal to control the fuel pump 38 and thus the supply of fuel to the combustion chamber 37.

22. A signal to the switching module 49 operable to provide the controller 48 delectively with d.c. output from the rectifier 46, the battery 52 or both.

23. Internal signals to the controller 48 from the individual wheel control modules 51, these being the input signals 5, as aforesaid.

24. A signal to the switching module 49 or the controller 48 to control the direction of the motors 50.

25. A signal to operate the valves 42 and 43 to bring the heat exchanger 41 into or out of circuit.

26. A signal provided by a sensor 26 to the controller 48 to draw power from the motors 50 to drive the alternator 45 alternatively as a motor.

27. A signal to the switching module 49 to charge the battery 52.

28. A signal to the switching module to operate back-up braking systems, which may be of electro-magnetic type.

Primarily the power management system 47 is under the control of the driver by his operation of either or both the pedals 54 and 55 which control the tractive effort demand either by varying the fuel supply to the prime mover or by braking.

These two controls could be combined into a single control. It should be emphasised that the pedal 54 is not a throttle-actuating pedal as in a conventional motor vehicle; that is it is not connected to the fuel pump 38. Instead the pedal 54 is an acceleration demand pedal and is connected only to the sensor 3 which transmits a signal to the power management system 47. The power management system 47 decides the response to movement of the pedal 54 dependent upon instantaneous signals received from all other sensors which transmit signals to the power management system 47.The microprocessor in the power management system 47 is programmed by interchangeable programmes 58 via signal 8 to increase or decrease the fuel supplied to the combustion chamber 37 to make the vehicle behave in the way required but also to endeavour to use the fuel in the most economical manner and particularly to maintain the speed of the low pressure shaft 30 and hence of the alternator shaft 44 substantially constant. The programmes 58 are interchangeable and can be supplied to give:- (a) Maximum vehicle performance; (b) Maximum vehicle economy; (c) Maximum engine performance; (d) Maximum engine economy, or (e) any other specif performance required, according to instructions programmed.

As the power management system 47 is responsive both to the extent and the rate of movement of the pedals 54 and 55, signals to the motors 50 can be effected to produce controlled braking or acceleration in response to the gradual movement of the respective pedal 55 or 54 or in response to sudden movement of the respective pedals 55 and 54 by the driver in an emergency.

The motors 50 are controlled automatically in accordance with the demand on the pedals 54 and 55 in combination with signals 6, 7 and 8 received from the devices 56 and 57 and from the pre-programmed device 58, and automatic adjustment is effected between the relative speeds of the motors 50, in accordance with the input signals 5 and output signals 23, whereby slip of any of the wheels 60 with the road surface is prevented or is controlled and the possibility of skidding is thus avoided or reduced. The sensor 26 supplies a chopped d.c. signal to each of the wheel driving motors 50 having a wave-form having an infinitely-variable mark/space ratio. The control modules 51 receive signals 6 from the wheel sensors 56 and thus adjust the power from the controller 48 by reducing it sufficiently for a slipping wheel or wheels to regain traction.

Cessation of wheelspin is signalled by one or more of the sensors 56 and 6 and so the corresponding control module 51 will now restore the power output from the controller 48 to the affected wheel motor 50.

In normal operation, receipt of a braking demand from the pedal 55 by the power management system 47 commands the controller 48. Additional braking may be effected by a signal 28 to the switching module 49 to bring in electrically-controlled mechanical brakes. In an emergency, the switching module 49 could reverse the polarity of the motors 50 and so effect driving of the wheels in the reverse direction.

During normal and emergency deceleration, signalled by gradually applied pressure on pedal 55, a signal 26 is applied by the power management system 47 to the controller 48 to apply a chopped d.c. output from the motor or motors 50 acting as d.c. generators to the alternator 45 in synchronism with the instantaneous phase signal 9 to drive the alternator as a motor. This will tend to maintain the speed of the low pressure rotor assembly of the prime mover constant and retard the vehicle and improve fuel demand and response time during subsequent acceleration demand signals from pedal 54. Thus the operation of the motors 50 as d.c. generators driving the alternator 45 as a motor provides regenerative, i.e., electrical, braking. As the speed falls, especially during emergency braking the power management system 47 will operate to provide additional mechanical braking, as aforesaid.Where there is excess power provided by the alternator 45, for example when the vehicle is coasting, a signal from the device 56 would control the switching module 49 in such a way as to permit the d.c.

output from rectifier 46 to charge the battery 52.

The alternator 45 when driven as a motor, by the battery, may be used to start the gas turbine.

Alternatively a separate starting motor may be provided and be powered by the battery.

Similarly when the operating pressure ratio of the gas turbine prime mover is allowed to fail to a predetermined level, the power management system 47 is used to reduce fuel consumption by operating the infinitely-variable heat exchanger control valves 42 and 43 to bring the heat exchanger 41 fully or partially into circuit, for example, under lowspeed traffic conditions, and conversely to take it fully or partially out of circuit when the power output demand increases.

As aforesaid, the memory and logic box 53 may be pre-programmed at 58 to provide any desired prime mover performance characteristic, for example, depending whether the vehicle is to be driven under urban traffic conditions or under higher speed cruising conditions on normal roads or under high speed conditions, for example on motorways, thus providing maximum fuel economy or maximum performance, as desired.

The pre-programming of 58 could be performed by the insertion of a key card or tape into the memory and logic box 53.

For operational duty cycles where transient overloads of brief duration may be demanded, e.g.

in road vehicle propulsion, the gas turbine component sizes may be selected so that maximum power output coincides with the maximum steady state power demand level, the power management system 47 being instructed to draw the transient demand in excess of steady state maximum demand from the battery supply.

Alternatively the gas turbine components may be designed to achieve optimum efficiency at maximum steady state demand level, excess transient demand being drawn from the gas turbine unit at a reduced efficiency level.

Advantages of the combined gas turbine alternator/battery system are that the combined efficiency is substantially constant; overall operational efficiency is high due to the regeneration of energy in the heat exchanger at low load and useful regeneration of energy during deceleration.

Numerous types of control can be effected by the power management system 47 and sq the input and output signals to the latter are not necessarily restricted to those signals or manner of using the signals as mentioned in this specification. For example, the motors 50 driving the wheels 60 or endless track-laying device on one side of the vehicle may be driven in the opposite direction to the motors 50 driving the sheels 60 or endless track-laying device on the other side of the vehicle, thereby to effect steering or to assist steering or directional control The power management system 47 can be employed to effect any control of the gas turbine unit or the vehicle which may be required.

Additionally all the accessories such as the fuel pump 38 and windscreen wipers would be driven by independent electrical power modules programmed by the power management system 47 either in respect of operational conditions or under the control of the driver.

The control and transmission system does not require a clutch or any reduction or other gears except where one motor 50 drives a pair of wheels 60 through a differential gear drive. The electrical circuitry and ail electrical components are of low cost and are extremely reliable and are of physically small size.

The gas turbine unit described is likewise reliable and includes no gear system. It has few parts and is simple to assemble and maintain and is small as it possesses extremely high specific power.

Claims

1. A vehicle power and transmission system comprising a prime mover; an electrical generator driven by the prime mover and from which a d.c.

output is derived; a battery providing an alternative d.c. output; at least one d.c. motor operable to drive traction-producing means of the vehicle and receiving either one of said d.c.

outputs; first control means connected to control the operation of said motor; switching means operable to control the application of at least one of said d.c. outputs to said motor through said first control means; second control means operable to control the prime mover; third control means operable to control the motion of the vehicle; microprocessor means connected to operate at least one of any of said switching means and said first, second and third control means; means providing signals derived from a plurality of driver-operable controls of the vehicle; first sensors responsive to prime mover operational functions; second sensors responsive to vehicle operational functions, and memory and logic devices associated with said microprocessor means, said microprocessor means being operable in response to input signals receivable from said means providing said derived signals, said first and second sensors and said memory and logic devices.

2. A system according to Claim 1 for a motor vehicle in which said traction-producing means comprises driven ground-engaging wheels or equivalent endless track-laying devices, the system having at least one said motor arranged to drive at least one pair of said ground-engaging wheels or said endless track-laying devices.

3. A system according to Claim 1 or 2 in which the electric generator is an alternator of the rotating field type arranged to be driven by the prime mover and the system also includes rectifier means connected to receive an a.c.

output from the alternator and to provide the aforesaid d.c. output for said motor or motors.

4. A system according to Claim 3 in which the alternator is of a high speed multi-phase type.

5. A system according to Claim 3 or 4 in which the rectifier means comprises one or more semiconductor rectifiers.

6. A system according to any preceding claim in which the prime mover is a gas turbine power unit.

7. A system according to Claim 6 in which the gas turbine power unit comprises twin-spool low and high pressure compressor and turbine assemblies, an intercooler between the low and high pressure compressors and a combustion chamber upstream of the high pressure turbine of the unit.

8. A system according to Claim 7 in which a heat exchanger is provided between the working fluid inlet to the combustion chamber and the exhaust from the low pressure turbine.

9. A system according to Claim 8 in which valve means are provided to control fluid flow through the respective heat exchange paths of the heat exchanger the valve means being one of said second control means operable by said microprocessor means,

10. A system according to any one of Claims 7-9 in which the intercooler has a downstream ejector pipe into which exhaust gases from the low pressure turbine are arranged to be discharged, thereby to draw air through the intercooler by ejector action.

11. A system according to any preceding claim in which the or each motor is of a disc type.

12. A system according to any one of Claims 3 to 5 in which means are provided to apply a chopped d.c. supply to said motor or motors thereby to effect operation of the motor or motors as a d.c. generator to drive the alternator as a motor and thereby to effect regenerative or electrical braking of the vehicle or to charge the battery.

1 3. A vehicle power and transmission system constructed and arranged substantially as described herein and shown in the accompanying drawing.