WO1982001170A1

WO1982001170A1 - Propulsion arrangement for vehicles

Info

Publication number: WO1982001170A1
Application number: PCT/SE1981/000280
Authority: WO
Inventors: Ab Carl W Andersson
Original assignee: Marlind G
Priority date: 1980-09-29
Filing date: 1981-09-28
Publication date: 1982-04-15
Also published as: EP0062044A1; GB2096079A; SE428782B; GB2096079B; SE8006788L

Abstract

Propulsion arrangement for vehicles comprising a first machine (1) arranged as propulsion engine driven by combustion of a propellant and a second machine (11) arranged as alternative propulsion motor driven by means of electricity from a battery (22). The battery is arranged so as to be charged with current generated by the work of the first machine. The propulsion arrangement is designed to work alternatively in a first operational state with the first machine as drive source for vehicle operation and for generation of current for charging the battery and a second operational state in which the second machine functions as drive source for the vehicle with supply of current from the battery. The second machine (11) is so arranged that during the first operational state it acts as generator and is thereby driven by means of the first machine (1) during generation of the said current for charging up the battery (22).

Description

Propulsion arrangement for vehicles

Technical fieId:-

The present invention related to a propulsion arrangement for vehicles and comprises an initial machine in the form of a motor arranged to be driven by combustion of a propellant and second machine arranged to be driven by means of electricity from a battery or to function as a generator. The object is preferably a propulsion, arrangement for load trucks for handling goods both in the open air and inside buildings.

Background:

The propulsion of vehicles by an internal combustion engine has certain advantages. The main one appears to be that the operating time between refuelling operations can be long and that the actual fuel filling operation can take place rapidly, which taken together provide long operating times; if so required practically the entire day can be utilised for operation.

Another important advantage is that the weight per horse-power for the motor and requisite fuel volume is low. Disadvantages which are linked with internal combus tion engines are mainly that they give pff harmful and dirty gases and have a relative ly high sound level. In spite of these dis advantages , internal combustion engine operation for vehicles is accepted outdoors , whilst there is an ever increasing tendency to prohibit and depart from its use indoors . An alternative propulsion system in which the said disadvantages are practically eliminated is propulsion by means of one or more electric motors , which for vehicle operation must be battery-driven. This method is often employed for load carrying vehicles , e . g. trucks , which are employed indoors or in any case for the most part indoors . However the disadvantage dees arise that with reasonab le battery size energy extraction between charges must be restricted whils t at the same time a maj or part of the day has to be reserved for battery charging. Furthermore the costs for maintenance and replacement of the batteries if operations are conducted solely with these is re latively high . As such a high weight - and this is incurred because of the batteries - is not a direct disadvantage for load-carrying trucks such as fork-lift trucks , because in any event a counterweight is essential, but even so energy extraction during a working day between re-charging periods often has to be restricted below the desirable level.

The said disadvantages of electric motor-driven vehicles are generally not particularly accentuated if these are operated solely indoors, because the rolling resistance and differences in level are relatively slight, whilst at the same time the distance traversed during a working day is relatively short. Furthermore if operations are conducted solely indoors there is hardly any other alternative. In the case of vehicles for combined outdoor and indoor operation however the conditions become more difficult. As already mentioned there is a tendency no longer to accept internal combustion engine operation for indoor use, whilst at the same time the demand for energy and power are high as a result of outdoor operation. During outdoor runs it is often necessary to traverse longer distances on uneven surfaces and with load carrying trucks the weight of the goods tends to be greater with outdoor operation than when operations are conducted solely inside buildings.

To solve the problem of being able to utilise the environmentally preferable method of electrical operation in doors, whilst at the same time having adequate energy and power available, the use has been proposed of hybrid machines for propulsion of vehicles. With these there is both an internal combustion engine and at least one electric motor, the said motors being capable of being used alternatively. The present invention relates to such a hybrid system and more particularly concerns a system in which the internal combustion engine is employed both for propulsion during certain operating periods, and simultaneously for charging up the batteries which are provided for operation of the electric motor, which in turn areonly employed for propulsion of the vehicle during limited periods, mainly during periods when the internal combustion engine is shut down. During outdoor operation the internal combustion engine is thus employed, whereby the batteries are charged at the sane time, whilst during indoor operation solely the electric motor is used.

When the power output is particularly high, possibly both machines can be employed. On the other hand the invention does not re late to sys tems of the type "diesel-electric operation" , i .e . constant propulsion with electric motors which are supplied, with electricity from a generator driven by an internal combustion engine and , periods when this is shut down , from batteries .

Technical problem:

However , the fact has emerged that such hybrid systems are inflexible when changing over - between the methods of drive , so that the vehicle has to be s topped when switching over and the purpose of the present invention is to provide a hybrid system of the above-mentioned type in which the changeover bet ween operation with the electric motor to operation with the internal combustion engine and vice versa can take place in a very flexible manner and whilst the vehicle is in motion.

Another objective is to provide an arrangement for switching over between the two modes of operation which is simple and ensures re liab le operation .

. The solution :

The solution in accordance with the invention involves the second machine , as motor , operating within a lower speed range , the first machine operating as motor within a higher speed range located above the lower speed range , the firs t machine being arranged to drive the second machine , and whereby a speed sensing arrangement is provided to switch over the second machine from motor operation to generator operation when , as a result of the operation of the firs t machine , the speed rises to the high speed range , and to switch in the seccnd machine as motor within the lower speed range .

Brief descript ion of drawings : The appended di agrams illustrate an embodiment of the invention . Fig. 1 gives a s chematic view of the driving machinery for a load-carrying truck and fig. 2 illustrates an e lectrical circuit diagram for the propulsion arrangement in accordance with the inventi on . Best mode of carrying out the invention :

In accordance with fig. 1 the propulsion arrangement for a vehicle , preferably a load-carrying truck , comprises an internal combustion engine 1 with a flywheel casing 2 , from which a drive shaft 3 proceeds on which a belt pulley 4 is fastened. A starting motor 5 , which can be driven by the current from a battery 6 , is provided to start the engine. A starting relay 7 is arranged in the battery lead for actuation of the starting motor 5 , and this relay can be actuated from a starting controller 8 , e . g. a press-button. Furthermore there is a stop button 9 , by means of which the motor can be stopped by influencing its injection pump or ignition arrangement 10, in the case of diese l engines or Otto engines.

Furthermore the propulsion arrangement comprises an electric motor 11 with a drive shaft 12 which has shaft journals at both ends of the motor. One shaft journal is connected to an hydraulic pump 13 which by means of pipes 14 is connected to hydraulic motors 15 , which are arranged to propel the propuls ion Wheels 16 of the truck. Furthermore , for regulating the flow from the hydraulic motor 13 , there are actuation pipes 17 which extend up to an actuating valve 18 designed as a pedal. A free wheel 19 via which a belt pulley 20 which is connected by belts 21 with the belt pulley 4 can drive the shaft 12 , is arranged at the other end of the shaft 12.

The shaft 12 which must always rotate during operation of the hydraulic pump 13 and thus during propulsion of..the vehic le by means of the hydraulic motors 15 has a defined direction of rotation. The free wheel 19 is thereby so arranged that it is engaged when the internal combustion engine 1 , which also has a certain drive direction on its output shaft 3 , drives the belt pulley 20 in the same direction as the defined direction of rotation of the shaft 12. - This signifies also that the free wheel free-wheels in the opposite relative direction of rotation , which means that for its part the shaft 12 cannot drive the belt pulley 20 and hence certainly not the internal combus tion engine 1 during independent operation in. the defined direction of rotation . In other words : if the internal comb ustion engine is in operation , but not the electric motor 11 , the internal combus tion engine drive the shaft 12 and thus the hydraulic pump 13 , whils t on the other hand if the in ternal com bustion engine 1 is not in operation , whilst the e lectric motor 11 is in operation , then the electric motor will run freely without entraining the internal, combus tion engine .

A battery 22 which can be connected by means of a relay 23 to the electric motor is provided for operati on of the electri c motor 11. The functioning of this relay will be explained later .

In what has been stated above the electrical machine provid ed has been designated as the electric motor 11. As such it is a lso envisaged to operate as a motor. However it is arranged to be ab le to function alternatively as generator , and it is then so connected to the battery 22 that the latter can be charged during operation of the generator . To draw attention to this point, in future the motor-generator will be designated as "the electrical machine 11" . Such a changeover can be performed re l a tively simply , generally by certain windings of the e lectrical machine being magnetised by supplying a field current, whils t at the same time other windings are connected up for e lectricity output. The relay 23 is provided for this changeover. When the relay 23 is engaged for motor operation , electricity is thus taken from the battery 22 so that the machine 11 is driven , whilst during generator operation current is fed to the battery 22 to charge this up .

Characteristic of the invention is the fact that this changeover between motor and generator operation is controlled by a speed-sensing arrangement. This can consist of a special speed-sensing arrangement , e . g . on the shaft 12 , and this has been designated as 24 in the circuit diagram in fig. 2. Alternatively , speed indication can be undertaken by recording the currents which flow through the windings of the e lectrical machine 11. Simultaneous ly with the fact that the re lay is arranged to be controlled during its changeover of machine 11 between notor and generator operation as a function of speed , the actual machine is arranged to operate within a certain speed range as motor , and at another speed range which lies above thi s speed range as generator. Speed control of the re lay is thereby so arranged that the changeover to generator takes place- when the rotational speed of the shaft 12 of machine 11 passes from the lower speed range up to the higher speed range , whilst changeover to motor operation takes place when the speed drops from the higher speed range to the lower speed range. Furthermore motor operation is obtained during s tarting up and the supply of current to the machine from the battery 22 , i. e . when starting from ze ro and passing to the lower speed range. Furthermore one of the characteris tics of the invention is that the internal combusti on engine 1 is arranged to drive the system within the higher speed range at the envisaged normal load range. In the embodiment illustrated thus the transmission ratio via the belt pulleys 4 and 20, is so adapted to the speed of the internal combustion engine 1 that during operation of the internal combustion engine the shaft 12 is driven at a rotational speed located within the higher speed range .

In fig. 2 the arrangement is illustrated in the form of an electrical circuit diagram where the components des cribed previous ly are reproduced with the same notation numbers . Furthermore , as mentioned, a speed sensing arrangement 24 is specified , which is shown in fig. 2 as being connected to the shaft 12. This can consist of some known arrangement of the centrifugal,eddy-current type or the like , which is capable of imparting a control signal in a conductor 25 to the changeover relay 23. turn the relay 23 cannot have solely a changeover function , but must also function as charging relay , so as to provide suitable charging of the battery 22. It is not necessary to describe in greater detail the starting arrangement for the internal combustion engine 1. The method is already known of arranging a small electric motor for starting up internal combustion engines. In the embodiment shown the starting motor 5 is connected to a special battery 6 and a special generator is then provided for charging up this battery . Thus the internal combustion engine 1 is quite simply a standard engine with associated starting equipment of the standard type . As such it is possible, within the framework of the invention , to combine the two electrical installations illustrated in fig. 2 , e. g. by connecting the starting motor 5 to the battery 22. It is also possible to allow the motor 11 to function as starting motor , although then the free wheel 19 must be replaced by some controlled shaft coupling. During the development of the invention however the method illus trated was found to be the most suitable.

As shown by the foregoing the drive thus takes place from the shaft 12 either by means of the electrical machine or the internal combustion engine. The drive power output is transmitted to the hydraulic pump 13 for which flow control arrangements are provided. This can for example be of the type which has a swivelling plate by means of which the stroke length of the pis tons can be controlled, whereby the outgoing flow can be varied infinitely even with constant speed of the input shaft. The pressure medium from the hydraulic pump is transmitted via pipes 14 to the two motors 15 and thus when the shaft rotates the wheels 16 are driven. Preferably the system is also provided with changeover valves so that reverse motion is possible. Such in finitely variable hydraulic systems form state of the art and do not need to be described in detail here. Flow regulation takes place by means of the said foot pedal via a remote actuation control arrangement which as shown in the diagram can be of the hydraulic type. The control range for pump 13 should be such that it should be possible to achieve the desired speed range during propulsion of the truck, regardless of whether the drive machinery, i.e. the shaft 12 , operates within the previously mentioned lower speed range during electrical operation, or the higher speed range during internal combustion engine operation. In other words it must be possible, by regulating the pump within the control range provided for it,, to compensate for differences in the speed of rotation of shaft 12 within both these speed ranges in such a manner that the speed of rotation of the wheels 16 can be maintained constant.

If we assume that the truck is to be started indoors, the battery 22 is connected to the electrical machine 11, which thereby rotates the shaft 12 and drives the pump 13. By means of control valve 18 the speed of wheels 16 can be controlled, so that it is possible to regulate the speed of the truck between zero up to thehighest envisaged speed. During rotation of shaft 12 the free wheel 19 is disengaged, so that the belt pulley 20 remains stationary and the internal combustion engine, 1 is not affected. During e lectric motor operation the speed control arrangement ens u res that an adequate coupling is obtained so th at current is supplied from the battery 22 to the machine 11 which functions as a motor. As shown by the foregoing, this takes pl ace at the lower speed range and, as long as this is complied with , the relay 23 ensures the said motor coupling.

If, for example , when driving out of the building internal combus tion, engine operation is required the engine is started in the conventional manner with its starting motor 5 by actuation of the starter control 8. As a result the engine 1 is started up and reaches its speed and the belt pulley 4 drives belt pulley 20. Since the belt pulley 20 is driven at a higher speed than the speed maintained by shaft 12 during electric motor operation , the free-wheel 19 is engaged and the shaft 12 increases its speeds to the higher speed range . As a result relay 23 is actuated by the said speed-sensing arrangement. This results in the machine 11 being switched over to generator operation. During this its field windings are energised and it starts to generate current, which , via the relay 23 which functions as charging relay, is transmitted to the battery 22 to charge this up . At the same time the pump 13 also starts to be driven at higher speed and the wheels 16 also try to be driven at higher speed from the hydraulic motors 15. As soon as the driver senses this he can compensate for the increasing speed of shaft 12 by releasing pressure slightly on the pedal to the control valve 18. This reduces the flow of pump 13 , so that the desired speed of rotation of wheels 16 is obtained. Very often howeve r the situation is that a higher speed is required when driving outdoors and naturally actuation of the pedal takes place in accordance with the driver ' s required running speed. As indicated however there is a possibility of speed compensation and for maintaining a uniform speed.

If the internal combustion engine 1 is overloaded,, either because the drive resis tance on wheels 16 becomes excessive or because any ancillary equipment present in the form of load-handling arrangements such as lifting forks or cranes is heavily loaded, the speed of the enginewill drop. If this occurs to s uch an extent that the speed of rotation of shaft 12 passes out of the specified higher speed range , then firs t of all generator ope ra tion of machine 11 will be disconnected , which signifies a lower loading. If the speed drops down to the lower speed r ange the relay 23 will change over machine 11 to motor operation and thus provides operation from both the internal combustion engin e

1 and the electricalmachine 11. As indicated , the two speed ranges can be located one after the other with an intermediate range in which the machine 11 is completely disengaged. The two ranges can also occur directly one after the other so that the relay is switched over between generator and motor operation without any neutral position . Preference should be given to the latter.

If the vehicle is to be driven Into a building once more the engine 1 is s topped using the step control arrangement 9 . As a result the speed drops to the lower speed range and the relay 23 now engages the machine 11 for motor operation with current being taken from the battery 22. As soon, as the shaft 12 starts to rotate more rapidly than the belt pulley 20, the free-wheel 19 is disengaged and the shaft 12 can rotate freely without being affected by the engine 1. The drive of pump 13 thus occurs by e lectric motor operation . The reduction in the flow from the pump which takes p lace during the transition to the lower speed range can thus be compensated , as des cribed above , by means of the control valve 18 which is provided with a pedal , if so re quired.

Industrial appl icabil ity :

Within the framework of the invention, as defined in the following patent claims the arrangement can be varied beyond what has been stated in the previous des cription. Thus the engin e 1 does not need to be an internal combustion engine of the typ e mos t widely employed now , i . e. a pis ton engine of the diesel or Otto type . It is also feasib le for it to be a Stirling engine , combus tion turbine or a steam engine . The essential thing is that the one drive source has characteristics which are not appropriate for driving in enclosed premises , whilst on the other hand it can easi ly be provided with the necessary drive means . These circums tances prevail with all types of engines and machin es which are driven by combus tion of a fuel in some manner or other. The connection illustrated, via a through shaft to the electrical machine, is not essential to the invention. For example a connection is feasible where the two machines are connectedin parallel with the power transmission. The latter also does not need to be of the hydraulic type, but some form of control of the transmission ratio should be provided to compensate for operation within the two speed ranges. It. is also possible to provide the arrangement with an element which automatically changes over the transmission ratio, on changing from one drive speed to another.

Claims

Patent claims :

1. Propulsion arrangement for vehicles and comprising a firs t machine (1) arranged as propulsion motor and thereby driven by combus tion of a propell ant and a second machine (11 ) arranged partly as alternative propulsion motor , thereby .driven by mean s of electricity from a battery (22) and partly as generator, thereby driven by means of the firs t machine (1 ) during generation of el ec tricity to charge up the battery (22) whereby the propulsion arrangement is designed to alternatively function in. a first operating s tate with the first machine as drive source for opera ting the vehicle and , if this be required , for generation of electricity for charging up the battery by operation of the second machine acting as generator , and a second operational state in which the seccnd machine functicais as drive source for the vehicle with supply of electricity from the battery , ch aracterised in that the second machine (11) is so arranged that in the second operational s tate as motor it operates within a lower speed range , that the first machine (1 ) is so arranged that in the first operational state it functions as motor within a higher speed range which is located above the lower speed range , that the first machine is arranged to drive the second machine duri ng its operation as propulsion motor and that a speed-sensing arrangement (23) is provided to change over the second machine from motor operation to generator operation when , as a result o f the work of the first machine , the speed rises to the higher speed range , and to engage the second machine as motor when t the speed is located within the lower speed range , so that of the two operational states the first can be achieved by bringing the first machine (1) into operation , whereby the higher speed range is normally reached and the second machine (11 ) functions as genera tor , or by shutting down the first machine whereby the second operational state involving the lower speed range is adopted and the second machine operates as motor.

2. Propulsion arrangement as in claim 1 characterised in that the first machine (1.) is arranged so that at heavy, loading it can operate in the lower speed range whereby when the lower speed is adopted under load the second machine (11) is caused by the speed-sensing arrangement (23) to change from generator operation to motor operation, by this means supporting the work of the firs t machine.

3. Propulsion arrangement as in claims 1 or 2 , characterised in that the firs t machine (1 ) and the second machine ( 11) are coupled in drive connection .with the same output drive shaft ( 12) whereby the first machine is coupled to the drive shaft by means of a free-wheel coupling (19) in such a way that when the firs t machine is in operation this can drive the output shaft via th e free-wheel coupling, whilst when it is not in operation the output shaft can rotate in the drive direction free-wheeling from the drive connection with the first machine .

4. Propulsion arrangement as in claims 1, 2 or 3 characterise d in that the first machine (1) and the second machine (113 are arranged to drive the propulsion mechanism of the vehicle via an hydraulic power transmission (13, 15) which is infinitely adjustable over at least a part of its speed range 5. Arrangement as in claim 4 , characterised in that the hydraulic power transmission (13,15) is infinitely adjustable within a range such that the envisaged difference in speed between driving by means of the first machine (1 ) with its higher speed and driving by means of the second machine (11) with its lower speed can be compensated for by varying the transmission ratio in the hydra ulic power transmission in such a way that the speed of propulsion of the vehicle can be maintained unchanged within the envisaged normal range of drive speed when changing over between the two machines as propulsion source .