WO2014079452A1

WO2014079452A1 - Starting device for an automobile engine or similar internal combustion engine

Info

Publication number: WO2014079452A1
Application number: PCT/DK2013/050372
Authority: WO
Inventors: Ole Olsson
Original assignee: Ole Olsson
Priority date: 2012-11-20
Filing date: 2013-11-12
Publication date: 2014-05-30
Also published as: DK201200729A; DK177759B1

Abstract

The present invention relates to a starting device for an automobile engine or a similar internal combustion engine, and more particularly of the type in which the initial power is supplied by a pre-tensioned spring (4), the accumulated energy (spring tension) of which is trigged under the startup process. The spring does affect the combustion engine via a boot drive (12, 13, 14), which is coupled to the engine flywheel (16, 17) during the startup process. The boot drive is automatically disconnected from the engine flywheel as soon as the engine rotates under its own power. The novelty of the invention lies in the fact that, in connection with the spring- operated boot drive, there is inserted an electric motor (5) with the object to tension the spring (4) before each start up process. The electric motor – in the following description named tension-motor (5) – affect the spring via a reduction gear drive (6) with relatively large exchange ratio. That allows the use of a relatively small tension- motor with an equivalent small current demand, and can therefore be driven by a Li- ion or Ni-MH battery. This battery types are more environmentally friendly than the traditionally today used lead-acid battery. Under normal circumstances the tensioning of the spring will take place while the combustion engine is running, i.e. while the engine electric generator produces electric power. Therefore the electric energy for the tensioning of the spring is delivered directly from the combustion engine itself. The Li-ion or Ni-MH battery serves only as a backup energy source for the spring- operated starting device, and is only to be used in special occasion. The advantage by the new starting device is that the electrical system and in particular the battery can be dimensioned for a much lower maximum current than in the normal combustion engine driven cars, where the direct-acting electric starter demands for a very high electrical power (current) during the startup process. These demands can only be accomplished with a lead-acid battery, not with Li-ion or Ni-MH batteries, and these environmentally friendly batteries are therefore no option today.

Description

STARTING DEVICE FOR AN AUTOMOBILE ENGINE OR SIMILAR INTERNAL COMBUSTION ENGINE

The present invention relates to a starting device for an automobile engine or similar internal combustion engine, and more particularly of that type referred to in the introduction of claim 1.

Car engines and others, especially smaller internal combustion engines are usually started using an electric self-starter. An electric self-starter is briefly described an electric start-assist motor, which is activated and connected to the internal combustion engines during the startup process. The connection is made via a pinion gear wheel, which engages a ring gear on the engine flywheel, and then the booster motor is activated. As soon the combustion engine rotates under its own power, the electric self- starter motor is coupled free of the ring gear and is deactivated (stopped). An electric self-starter, that means the booster motor, to a 4-cylinder car engine of 1,2 - 1,6 liters displacement typically have an effect in the order of 0,5 - 1,0 kW. The electric self- starter or booster motor is hereafter called the starter.

During the enforced starting rotation of the combustion engine the starter has to deliv- er a torque, which is sufficient to overcome the internal friction and compression of the combustion engine, and at the same time the starter should have enough effect to accelerate the combustion engine up to a speed, at which the combustion engines are able to proceed under its own power, provided proper ignition and fuel supply. The starter to a car combustion engine is usually a DC-electric motor, which is wound as a series- or a compound motor. Both motor types are characterized by a high starting torque. The high starting torque presupposes that the battery, that supplies the starter with electric energy, is able to provide the necessary high current that is required during the starting process. The inrush current for a typical automotive starter is in the order of 100 to 400 amperes, during cold start condition in the winter even higher.

The battery type used as starting battery for car engines are predominantly of the lead- acid type, also known as lead-acid batteries. Other rechargeable batteries, for example NiMH batteries and Lithium ion batteries, are unfit for the purpose, since the very high power output during the startup process will tear down the battery in short time. With the current battery technology the lead-acid battery (or lead-acid accumulator) is in practice the only type that is suitable for the purpose, price and durability taken into account.

In environmental terms, the conventional starter battery is problematic because of the lead content. The service life of a lead-acid battery is at best 6 - 8 years, and then the battery must be replaced. Consumption of lead-acid batteries for the entire car fleet is therefore considerable. Despite environmental programs to ensure collection of waste lead-acid batteries and recycling of the lead content in the batteries, in practice there will be some loss of leads that ends up as pollution in the environment. It should become a major effort to eliminate environmentally harmful heavy metals, including lead, from the environment in accordance with the RoHS directive, and it must be expected that the lead containing starter batteries for cars probably will be banned in the future.

One has tried to make the starting device more environmentally by utilizing (recyclable) the inertia still remaining in the combustion engine in the short time that passes from the engine ignition is switched off and until the engine actually stand still. The residual inertia represents a certain energy, which under normal circumstances (i.e. in a combustion engine equipped with a traditional starting device without energy recovery) is wasted as frictional losses in the engine. Recycling of the inertia can for example be realized by mechanical switching the engine with a spring-based startup device during the deceleration (i.e. the stop-period). The switching result in, that the remain- ing inertia in the engine is transformed to a tensioning of the spring integrated in the starting device. That means the spring function as an energy accumulator. When the combustion engine has to be started up again the spring tension is released, and the released accumulated energy is then used to rotate, that means to start, the combustion engine.

A starting device of the mentioned art is known from the description to DE 102007032316 Al (BMW). The descripted starting device is designed for an automobile combustion engine, wherein the starting effect at least in parts is produced by an auxiliary motor, which is a battery-powered electric motor. The auxiliary motor is equipped with a power drive-line, which includes an engagement gear, in the following named pinion gear. The pinion gear is brought into engagement with a ring gear mounted on the combustion engine flywheel during the start-up process. The engagement is obtained by an axial displacement of the pinion gear until the teeth on that is in full engagement with the teeth of the flywheel ring gear. First when this engagement is established the starting device is activated. When the combustion engine rotates by its own power the pinion gear is displaced free of the teeth-engagement with the flywheel ring gear again. The electric auxiliary motor functioning in combination with a spring driven motor, which includes a spring, which is tensioned under the action of the remaining inertia in the combustion engine, when the engine is stopped, and which gives its accumulated spring energy back again to the combustion engine, when the engine is started. To enable this alternating function of the spring, wherein the spring partly has to be ten- sioned by the combustion engine, which naturally occurs in that specific rotation direction determined by the combustion engine, and partly gives the accumulated spring energy back to the engine again, when the engine is started, and this time in the opposite direction determined by the spring itself, it is necessary to incorporate a reversing gear in the drive line between the engine and the spring to ensure, that the engine is activated (started) in the correct rotation direction. This reverse gear and the conversion of the gear seriously complicate the mechanical design of the starting device.

Another technical challenge by the starting device known from DE 102007032316 Al is to create a mechanically reliable and durable coupling mechanism between the spring and the combustion engine, so that the switching on of the spring to the combustion engine can be completed with the necessary security. It is noted that the switching on of the spring take place every time, the combustion engine is stopped, and that the switching process take place while the engine is still rotating. In practice, the coupling mechanism may be expected to give rise to significant technical prob- lems, especially when the starting device, which is exactly the intention of the invention, is a part of a so-called start-stop engine solution, where the frequency of engine starts is great. In cases where the switching on process, and thus the tensioning of the spring fails - it may be situations, where the engine is stopped unplanned or un-intentioned but provoked on the one or another way - the electric auxiliary motor alone has to be able to start the combustion engine. I.e. the electric auxiliary motor must necessarily be de- signed and dimensioned as a traditional direct-acting electric dc-starting motor, and this starting motor must be connected to a battery, which has sufficient capacity to meet this starters needs. In other words, and according to the explanation above: the starting device according to DE 102007032316 Al assumes, that the car is equipped with a starting battery of the traditional lead-acid type. I.e. DE 102007032316 Al re- solves in no way the problems related to the RoHS Directive and the use of lead in cars.

The intension of this invention is to provide an electric and spring based starter device which is not based on or dependent on a lead-acid starter battery. Essentially pursues a solution where even smaller rechargeable batteries of the NiCa type, NiMH type or Lithium ion type are sufficient to cover the need for power of the starter, and therefore can be used as a starter battery.

The task is solved according to the present invention by a starting device as specified in the characterizing part of claim 1. The novelty of the invention consist in that the auxiliary power unit (the starter) is a spring-driven motor which includes a torsion spring, one end of which is coupled to a small electric motor. This electric motor is arranged to twist, i. e. tension, the torsion spring until a certain tension level, while maintaining the other end of the torsion spring fixed. The electric motor draws the torsion spring via a suitable reduction gear drive. The said electric motor is in the following description named the twisting electric motor.

The second end of the torsion spring is coupled rotationally locked together with a ratchet wheel, which is journalled rotatable on a shaft, and which is provided with a releasable ratchet with its blocking direction opposite the twist or tension direction of the torsion spring. Said ratchet wheel is at the same time coupled with said pinion gear wheel (the gear wheel which can be brought into engagement with the ring gear on the flywheel) via a gear transmission, or through some other type of mechanical transmission between the pinion gear wheel and the ratchet wheel. The arrangement ensures that the accumulated spring tension in the torsion spring is transformed into a rotation of the ratchet wheel and thus of the pinion gear wheel when said ratchet wheel is released by the ratchet. The pinion gear wheel rotation force in a conventional manner the combustion engine to rotate. This take place during the starting process, in which the pinion gear wheel in advance is brought into engagement with the flywheel ring gear, as described above.

The advantage of the new spring driven starting device is that the twisting electric motor, with which the torsion spring is tensioned, can be dimensioned for a much smaller battery capacity and much lower electric current compared with the today used direct-acting electric starter motors. Under normal circumstances the tension of the torsion spring takes place in the first few minutes after the engine start-up that is to say when the engine is working (rotates). Therefore the twisting electric motor can be supplied with electric power directly from the electric generator on the combustion engines, not from the battery. This practice contribute to preserve the battery and to give the battery the longest possible lifetime.

In the more special cases where a starting attempt fails, i. e. where the combustion engine fails to run, and the torsion spring therefore must be re-clamped before the next start attempt can be launched, it is obviously necessary to draw electric power from the battery. However, this can be done without any overloading of the battery. The condition is, that the battery is properly dimensioned compared with the twisting electric motor. The size of the twisting electric motor and the gearing between the twisting electric motor and the torsion spring is selected based on the time that will be accepted between two successive start attempts. With a bigger twisting electric motor the re- tension of the torsion spring can be done quicker, but the battery dimension must be equivalent bigger to avoid overload of the battery.

It should be noted in this context that modern car engines (gasoline engines) is ex- tremely starting willing thanks to the electronic ignition systems and fuel injection systems the modern cars are equipped with. The same applies to modern automotive diesel engines. As a result of the new engine technology a modern car most likely will start within one or as highest two engine revolutions. Combustion engines, which does not start at first attempt, will in practice be an extremely rare occurrence, and therefore the disadvantage of not being able to implement two or more start attempts without waiting time between each start attempt can be ignored.

In a preferred embodiment of the invention the torsion spring is a helical spring which is fitted concentrically around a through-going spring shaft, which is journalled in its ends. The through-going spring shaft is in one end fitted with a gear wheel, in the following referred to as the torsion-gearwheel, which is rotatable fixedly connected to the helical spring in that end. The torsion-gearwheel is also engaged with a reduction drive gear belonging to the twisting electric motor. The twisting torque for tension the helical spring is transferred from the twisting electric motor through this reduction drive gear to the torsion-gearwheel and from the torsion-gearwheel to the helical spring.

The through-going spring shaft is in the opposite end fitted with a ratchet wheel, which is rotatable fixedly connected to the helical spring at that end. The torsional deformation of the helical spring that occurs during the torsional tension process is thus distributed all over the helical spring length between the torsion-gearwheel and the ratchet wheel. The through-going spring shaft helps to support and stabilize the helical spring, especially in cases where the helical spring has a great length relative to the spring diameter and thread thickness.

The embodiment is distinguished by being constructive simple and by allowing a compact structure of the starting device. The construction ensures that the elastic deformation ability of the helical spring is exploited optimally. Appropriate both the torsion-gearwheel and the ratchet wheel are journalled concentrically on the through- going spring shaft, and such that at least one of the two wheels is rotatable journalled on the shaft, whereas the other wheel on the same time being fixly mounted on the shaft. In this way the through-going spring shaft is integrated in the construction as a force receiving element and contributes to harness the considerable forces that inher- ently occur, when the helical spring is twisted.

A special problem in connection with a starting device of the type in which a pinion gear wheel has to be engaged with the teeth of the ring gear on the engine flywheel before the starting effect can be trigged, is related to the fact that the action requires the gear tooth on the two gear wheel (pinion gear wheel and flywheel ring gear) to correspond to each other before the pinion gear wheel can be pushed into action position in engagement with the tooth on the flywheel ring gear. In other words, there must be established a match between the two gear wheels before the starting process can be initiated. This problem is solved in a conventional starter by operate the starter- motor with reduced current at the time, when the electromagnet used to slide the pinion gear wheel forward against the flywheel ring gear, is activated. The starter-motor then rotates with reduced torque and speed. This allows in a primitive way the teeth to "get together", i. e. to create the desired match. Once the match is established, the electromagnet is able to slide the pinion gear wheel into full gear engagement with the flywheel ring gear. Only when the full engagement is established a start relay controlling the full current to the electric starter motor is activated, and the starting process then occurs. By the starting device according to the invention it is not possible to let the starter (i.d. spring driven start motor) to run with reduced torque and/or reduced speed at an initial stage of the starting process to secure the match between the two sets of teeth. The problem is instead solved by an arrangement as specified in claim 4. In this embodiment the ratchet is mounted on a swing arm, which stands under action of an electric motor, electromagnet or other external actuation force applied to the swing arm. With the actuating force the swing arm, and thus also to the ratchet, are set in a forward and backward movement between two end positions. The movement of the ratchet is transmitted to the ratchet wheel as a result of the engagement between these two elements (the ratchet and the ratchet wheel). The ratchet wheel is therefore forced to perform a reciprocating rotary motion, and this motion is transmitted to the pinion gear wheel, which, as already described, is in mechanical transmission with the ratchet wheel. The result is that the pinion gear wheel performs a reciprocating rotary movement under which the desired match between the two sets of gear teeth occurs. The rotational movement of the pinion gear wheel may in practice be limited to an angular range that is at least equivalent to the width of a single tooth on the gear wheel. In a preferred embodiment the actuating force for moving the swing arm is submitted by the action of an eccentric drive mechanism, which is connected to the swing arm by a connecting rod or a link arm connection of another suitable art. The eccentric drive mechanism is connected to the reduction gear of the twisting electric motor via a transmission shaft. In this relatively simple way one obtain that the pinion gear wheel perform the mentioned reciprocating movement during the tightened up of the helical spring. By continuing (or resume) the tension process simultaneous with the initiated start procedure, i. e. while the pinion gear wheel is pressed forward against the flywheel ring gear, the teeth on the pinion gear wheel will automatically find a match with the teeth on the flywheel ring gear. The embodiment means, that you save a separate electric motor or electromagnet to produce the reciprocating movement of the pinion gear wheel.

Another embodiment, which is based on the same principle as described above, is special in that the eccentric drive mechanism is constituted by a rotating eccentric pin, which engages in a guideway integrated in the swing arm. The swing arm is journalled pivotable about the through-going spring shaft with its pivot center in the axis of this shaft. The eccentric drive mechanism is driven from the twisting electric motor as mentioned above. The solution is characterized by its simple construction and by ena- bling a very compact embodiment of the total starting device.

In order to further improve the initial boot process, where the pinion gear wheel has to be brought into engagement with the teeth of the flywheel ring gear on the fastest and most effective way, it is proposed according to the invention to supply the starting device with a system of non-contacting electronic sensors, e.g. inductive sensors or photocells, placed next to the flywheel ring gear. The electronic sensors have the object to register the exact position of the teeth of the flywheel ring gear when the engine is stopped. Also the pinion gear wheel can be fitted with a similar system of non- contacting electronic position sensors to record continuously the exact sprocket posi- tion. The sensor system may also be based on a step- or angel encoder coupled to the pinion gear wheel.

The two sensor systems (on the flywheel and on the pinion gear wheel) are connected to a common electronic control unit, which may be based on a microprocessor. The object of this electronic control unit is to control the twisting electric motor on the basis of records of the sprocket position received from the two sensor systems. The program will then be able to ensure, that the twisting electric motor stop in an exact position, where the teeth of the pinion gear wheel match the teeth of the flywheel ring gear. That means, the gear teeth will be able to immediately slide into each engagement when activated. The electronic control unit ensure in this way that the boot process can be carried out quickly, efficient and without teeth "scratching" against each other. Also this will increase the lifetime of the pinion gear wheel. It is noted that the torsion spring of the starting device is first trigged, when the pinion gear wheel is shot all the way forward, i.e. when the full engagement between pinion gear wheel and the flywheel ring gear is obtained. The release of the spring effect is achieved by release the ratchet wheel ratchet. In a preferred embodiment the ratchet is provided with a direct acting electromagnet, with which the ratchet can be released. Alternatively the ratchet can be arranged so, that a mechanical release mechanism is connected to the electromagnet, with which the pinion gear wheel is pushed forward to the start position in engagement with the flywheel ring gear. In this embodiment it is ensured in a very simple manner that the ratchet first is released when the full engagement between the pinion gear wheel and the flywheel ring gear is obtained. The connection between the ratchet and said electromagnet may be achieved by mechanical means in different ways, and will not be further described here.

In order to prevent the twisting electric motor to rotate reverse the tension direction when the electrical activating of the twisting electric motor stops after complete ten- sion of the torsion spring, it is according to the invention appropriate to provide the starting device with a backstop mechanism that is integrated in the reduction drive of the twisting electric motor. The backstop can alternatively comprise a second ratchet wheel that is inserted on the through-going spring shaft and in fixed connection with the torsion-gearwheel. The ratchet wheel is provided with a spring-loaded ratchet for locking in a direction opposite tension direction.

To use in cars the new spring driven starting device excel by eliminating the lead containing start battery. Instead the car is equipped with a much smaller and in environmental terms les harmful Lithium-ion battery. The battery is necessary for ignition during the boot process, and for the operation of the functions in the car, which also has to work when the engine is stopped, e.g. hazard flashers, parking lights, remote door locks, etc. The Lithium-ion battery is recharged from the engine electrical generator in usual way while driving. Since the Lithium-ion battery only exceptionally has to provide initial help to the engine, the battery capacity can be reduced quite substantially compared to an equivalent lead-acid start battery traditionally used in cars with a direct acting electric starter.

The replacement of the lead containing start battery with a Lithium-ion battery also include the advantage, that the electrical system in the car easily can be adapted to a higher voltage than the today standard 12 vdc. The 12 vdc standard voltage is partly determined by the internal structure of the lead-acid battery. If you wish to increase the voltage of the lead-acid battery the number of cells inside the battery must be increased. This means a bigger and heavier battery or alternatively a reduced distance between the cell plates. This affects the resistance against shock and vibration.

The Lithium-ion batteries are not limited in the same way. Lithium-ion batteries are mass produced and marketed in the form of sealed battery packs with voltage up to 24 volt and a capacity up to 4,0 Ah per pack. Rechargeable battery packs of this type, e.g. designed for hand tools and the like, will simply be able to replace the today standard lead-acid start batteries for cars. Lithium- ion batteries arranged in packs are robust to shocks and vibrations, and there lifetime is fully sufficient for the purpose, provided the batteries are not often subjected to deep discharge cycles. And this will just not occur when the car is equipped with a spring driven starting device of the described new type explained above.

An increase of the voltage from 12 vdc to 24 or 48 vdc will provides the following advantages:

• All electrical components of the car can be made smaller and lighter. Results:

Weight saving and less consumption of metal and copper.

· All cables in the extensive wiring of a modern car can be selected with reduced copper cross-section. Result: weight saving and less copper consumption.

• The electric system in the car can be made more reliable and resistant to moisture. Result: fewer operational problems and fewer visits to the workshop. Overall, a number of advantages which means a desirable weight reduction and savings in the production.

The invention will be explained in more detail below in connection with the drawing, in which:

Fig. 1 shows a spring driven starting device in a first embodiment of the invention, shown in longitudinal section,

Fig. 2 the starting device shown in cross-section along the line A-A of fig. 1, Fig. 3 the cross section shown in enlarged view and with the reciprocating move- ment shown in end positions with dashed lines,

Fig. 4 shows a starting device in a second embodiment of the invention, shown in longitudinal section,

Fig. 5 the starting device shown in cross-section along the line B-B of fig. 4, Fig. 6 shows an enlarged section marked "C" of this sectional view, and

Fig. 7 is a sectional view taken along the line D-D in figure 6.

In the first embodiment shown in figure 1, 2 and 3 the starting device substantially consist of a casing 1, in which a through-going spring shaft 2 and a motor shaft 3 is embedded. Also the starting device include a helical spring 4 concentrically inserted on the through-going spring shaft 2, a twisting electric motor 5 with an integrated reduction drive 6 and a backstop 7. Further a torsion-gearwheel 8 fixed mounted in the one end of the through-going spring shaft 2, and in the other end of this shaft a rotatable mounted ratchet wheel 9, which at the same time functions as a gear wheel. Further a swing arm 10 rotatable mounted on the through-going spring shaft 2, and fitted with a ratchet 11 for the ratchet wheel 9. Further a pinion gear wheel 12 mounted slideable on a splined shaft 13, a backstop mechanism 14 inserted in connection with the pinion gear wheel 12, and an electromagnet 15 with the function to slide the pinion gear wheel 12 forward to engagement with the flywheel ring gear on the combustion engine. In figure 1 the flywheel and the ring gear are indicated by dashed lines. The flywheel is indicated by 16 and the ring gear with 17. Otherwise the combustion engine is not shown in the drawing.

The torsion-gearwheel 8 is, as mentioned above, rotatable mounted in one end of the through-going spring shaft 2, and meshes with a smaller drive gear 18 on the motor shaft 3. The torsion-gearwheel 8 is provided with a protruding hook-pin 19, which is in engagement with a bended eye-shaped end 20 of the helical spring 4 so that the torsion-gearwheel 8 will be able to clamp the spring by turning around its own axis. This turning is effected by the twisting electric motor 5, which engages the torsion- gearwheel 8 via the reduction drive 6 and backstop 7.

At the opposite end of the through-going spring shaft 2 the said rotatable ratchet wheel 9 is mounted. The ratchet wheel 9 is journalled on a set of ball bearings 21 inserted on the shaft 2, and operates as already indicated both as a ratchet wheel and a gear wheel. The gear wheel is engaged with a third gear wheel 22. This gear wheel 22 is fixed mounted on the splined shaft 13 of the pinion gear wheel 12. The helical spring 4 is inserted on the through-going spring shaft 2 between the torsion-gearwheel 8 and the ratchet wheel 9, and operates in the described setup as a torsion spring. Said ratchet wheel 9 is for that purpose provided with a protruding hook-pin 23, which is in en- gagement with a bended eye-shaped end 24 of the other end of the helical spring 4. The ratchet 11 is arranged with its blocking direction opposite to the tension direction of the helical spring 4, and will in this way prevent the helical spring to defuse by rotating in the tension direction, see figure 2. The ratchet 11 is, as mentioned above, mounted on the swing arm 10, which in turn is mounted on the through-going spring shaft 2 with the pivot axis of the swing arm coincident with the center axis 25 of the through-going spring shaft 2. The swing arm 10 is located in the space between the ratchet wheel 9 and the one end wall 26 in the casing 1. The other end wall in the casing 1 oppose to the first end wall 26 is indicated with 27. The through-going spring shaft 2 is journalled in bronze bearings 28 and 29 integrated in the two end walls 26 and 27, see figure 1.

The ratchet 11 is held by a not shown spring in close contact against the teeth 30 of the ratchet wheel 9, and prevents in this way the ratchet wheel to rotate backwards under action of the tension force of the helical spring 4, i.e. in the tension direction. The tension direction is shown in figure 2 with an arrow 31. The ratchet 11 can be released by action of an electromagnet 32, which is mounted on the swing arm 10. The electromagnet 32 is connected with the ratchet 11 through a link arm 33. The swing arm 10 is under effect of an eccentric drive mechanism 34, which is connected to the swing arm 10 through a connecting rod 35. The eccentric drive mechanism 34 consist essentially of an eccentric disc 36, which is inserted in a corresponding bearing bore 37 in the one end of the connecting rod 35. The other end of the con- necting rod is linked together with the swing arm 10 in a bearing point 38 (see figure 3).

The eccentric disc 36 is fixed mounted on the motor shaft 3, which continues all the way to the opposite end wall 26 in the casing 1. A slide bearing 39 integrated in the end wall 26 supports the shaft 3 in its free end. During the rotation of the twisting electric motor 5, when tightening up the helical spring 4, the eccentric drive mechanism 34 is also activated. The activation consist in, that the rotation of the twisting electric motor 5 is transferred to the eccentric disc 36 via the motor shaft 3. In this way the eccentric drive mechanism 34 effect the swing arm 10 to perform a recipro- eating swing movement, and together with the swing arm 10 the ratchet wheel 9 also perform a reciprocating turning movement. The reciprocating turning of the ratchet wheel 9 is effected by the connection with the ratchet 11, which is mounted on the swing arm 10. The reciprocating turning is illustrated in figure 3. Via the mentioned third gear wheel 22, which is mounted on the pinion gear shaft 13 in connection with the pinion gear wheel 12, and which is in engagement with the toothing 30 of the ratchet wheel 9, the reciprocating turning is transmitted to the pinion gear wheel 12. It is noted, that the reciprocating movements, as illustrated in figure 3, is somewhat enlarged just to clarify the movement principle. The needed minimum reciprocating angel of the pinion gear wheel 12 is similar to the width of a single tooth on the gear wheel 12.

The pinion gear wheel 12 and the associated clutch mechanism consisting in the splined shaft 13, the backstop 14 and the electromagnet 15 largely correspond to prior art solutions for car engine starters. The electromagnet 15 is connected to a lever arm 40 via a link arm 39. The lever arm 40 is fitted with two opposite pins 41. These pins 41 are engaged in an annular grove 42 in a guide disk 43 mounted axially slidably on the splined pinion gear shaft 13. The pinion gear wheel 12, the backstop 14 and the guide disk 43 together form a single block, that is rotationally locked, but at the same time axially slidably mounted on the splined shaft 13. By action of the electromagnet 15 and via the link arm 39 the lever arm 40 is moved backward in direction against the electromagnetl5. At the same time the free end of the lever arm 40 is moved forward in direction against the flywheel 16, and this movement is transmitted to the disk 43 via the two pins 41. This effect the pinion gear wheel 12 to move into contact with the flywheel ring gear 17 until full engagement between the two sets of teeth is established.

At the time when the electromagnet 15 is activated, also the twisting motor 5 is activated. For this purpose at least 2 - 3 % of tension capacity of the helical spring 4 is reserved to this stage of the boot process. When the twisting motor 5 rotates also the pinion gear wheel 12 is activated, i.e. perform the reciprocating movement as described above. The reciprocating movement of the pinion gear wheel 12, carried out simultaneously with the sliding of the pinion gear wheel 12 against the flywheel ring gear 17, brings the two sets of teeth to match and to engage each other. The pinion gear wheel 12 can therefore be pushed right up to fully engagement with the ring gear 17. In that same moment this occur the ratchet 11 is activated by the electromagnet 32 and the helical spring 4 is released. Now the starting device turn the combustion engine to start as already described. As an alternative to this kind of engagement between the two sets of teeth (pinion gear wheel 12 and flywheel ring gear 17) it is possible according to the invention to design the starting device in another embodiment to ensure, that the teeth match in advance, i.e. before the starting process is initiated. This means, that the pinion gear wheel 12 without problems immediately can kicks into the flywheel ring gear 17. To achieve this important property is next to the flywheel ring gear 17 arranged a system of non- contacting electronic sensors for sensing and recording the teeth position when the engine is stopped. These sensors, which may be inductive sensors or photocells, are not shown in the drawing. At the same time, there is another system of sensors continuously recording the teeth position on the pinion gear wheel 12. This second sensor system comprising a toothed disc 44, which is mounted in fixed connection with the pinion gear wheel 12. The toothed disc 44 is sensed by one or more sensors 45 (inductive sensors or photocells). Alternatively the pinion gear wheel 12 may be connected to an electronic encoder to continuously detect gear wheel position. The gearwheel control system further include an electronic control unit to control the twisting electric motor 5 on basic of the records of the tooth position relatively to each other in the two sets of gear wheel (12 and 17). Before the stating process is initiated, i.e. before the electromagnet 15 is activated, it is in this way possible to park the pin- ion gear wheel 12 in a standby position, where there is a match between the two sets of teeth.

This is done as follows. When the helical spring 4 is clamped near the mentioned 2 - 3% rest of the total tension potential in the spring, and when the combustion engine is stopped and stand still, the teeth position in the two sets of gear wheel are registered. If there is no match between the two sets of teeth, the twisting motor 5 is activated until the match is obtained and registered by the sensors. The activating can be done with reduced voltage, so that the twisting motor 5 rotate at reduced speed. In this way the "parking" of the pinion gear wheel 12 can be carried out with sufficient precision. Starting device remains in the set standby position until the next start process is initiated.

The second embodiment shown in figure 4 differs from the previously described first embodiment by having the torsion gearwheel 8 and the ratchet wheel 9 located at the same end of the through-going spring shaft 2. Apart from that the two embodiments includes the same elements and there functionally are virtually identical. The difference between the two embodiment consist in that the swing arm 10 in the second embodiment is embedded between the torsion gearwheel 8 and the ratchet wheel 9 with the through-going spring shaft 2 as pivot axis. The swing arm 10 is provided with a suitable milled recess 50 in which an eccentric 51 is slideably nested. The eccentric 51 is composed of an eccentric disc 52 and a ball bearing 53. The eccentric disc 52 is rotatable fixed mounted on a shaft 54 extending from the reduction gear 6 of the twisting motor 5. When the twisting motor 5 is activated to clamp the helical spring 4 by rotation also the eccentric 51 is rotated. And this rotation brings the swing arm 10 to perform a reciprocating movement. The reciprocating movement is transferred via the ratchet wheel 9 and the gear wheel 22 to the pinion gear wheel 12 as already described. This second embodiment allowing a very compact and robust design of the eccenter mechanism of the starting device. It should be noted that the two above described embodiment are both only schematically shown in the drawing. In practice the spring starting device can be constructed more compact than shown, and of course it is taken into account, that the starting device adapt the specific engine model. The invention is not limited to the two embodi- ment described.

Claims

1. A starting device for an automobile engine ore similar internal combustion engine, in which the starting power is generated by an auxiliary motor, which is typically a battery powered electric motor, but can also be a pneumatic motor or other type of motor; the said auxiliary motor is provided with a boot drive, which comprise an engaging gear wheel, in the following named the pinion gear wheel (12), which is brought into engagement with a toothed ring gear (17) mounted on the internal combustion engine flywheel (16) during the startup process, which action typically occurs by an axial displacement of the pinion gear wheel (12) until the teeth of this is in en- gagement with the teeth of the flywheel ring gear (17) followed by an activating of the auxiliary motor, and wherein the pinion gear wheel (12) is moved clear again of the teeth engagement with the flywheel, when the internal combustion engine is rotating under its own power,

characterized in that

- the auxiliary motor is a spring driven motor which includes a torsion spring (4), one end of which is coupled to an electric twisting motor (5), as with electrical activation and through a reduction gear drive (6) is arranged to twist, i.e. tensioning, the torsion spring (4) up to a certain tension condition, and the opposite end of the torsion spring (4) is rotatable fixedly connected with a rotatable ratchet wheel (9), which is provided with a releasable ratchet (11), the stop direction of which is opposite the tensioning direction, and

- there is established a mechanical transmission between the ratchet wheel (9) and the pinion gear wheel (12) via a gear transmission (22) or through a clutch mechanism in the one or other way to convert the accumulated tension energy in the torsion spring (4) to a rotational movement of the ratchet wheel (9) and thus the pinion gear wheel (12), which rotational movement is trigged during the startup process by releasing the ratchet (11).

2. A starting device according to claim 1, characterized in that the torsion spring is a helical spring (4), which is mounted concentrically around a through-going spring shaft (2), which is journalled at its ends (28, 29) and which at one end carries a gear wheel, hereinafter referred to as torsion gear wheel (8), which is rotatable fixedly connected to the torsion spring (4) in that end, that torsion gear wheel (8) is also in engagement with a drive gear (18) connected to a reduction drive gear (6) on the twist- ing motor (5), and wherein the through-going spring shaft (2) at its opposite end carries the said ratchet wheel (9), which is rotatable fixedly connected to the torsion spring (4) at that end, so that the twisting deformation of the torsion spring caused by the tensioning of the spring, is spread throughout the hole length between the torsion gear wheel (8) and the ratchet wheel (9).

3. A starting device according to claim 2, characterized in that both the torsion gear wheel (8) and ratchet wheel (9) is mounted concentrically on the through-going spring shaft (2), and such that at least one of the two wheels is rotatable journalled on the shaft, while the other wheel at the same time being fixed mounted on the shaft.

4. A starting device according to claim 1, characterized in that

- the ratchet (11) is fitted to a swing arm (1) which is activated by an electric motor, electromagnet or other external activating means to produce a reciprocating movement of the swing arm between to end positions, in which the ratchet (11) too perform this reciprocating movement and transmit this movement to the ratchet wheel (9) forcing this to pivoting back and forward in a limited angular range, and

- that said mechanical transmission (22) between the ratchet wheel (9) and the pinion gear wheel (12) cause the pinion gear wheel (12) to participate in the reciprocating pivoting movement.

5. A starting device according to claim 4, characterized in that the reciprocating pivoting movement of the pinion gear wheel (12) is within an angular range that is at least equal to the width of one gearwheel (12) tooth, and that the swing arm (10) has its pivoting center in the center axis (25) of the through-going spring shaft (2), around which the helical spring (4) is mounted.

6. A starting device according to claim 4, characterized in that the activating force for moving the swing arm (10) is caused by an eccentric drive mechanism (34) which is connected to the swing arm (10) via a connecting rod (35) or a similar join member with pivoting joints, and that the eccentric drive mechanism (34) is driven by the twisting motor (5) via a transmission shaft (3), which connect the twisting motor reduction gear drive (6) with the eccentric drive mechanism (34).

7. A starting device according to claim 4, characterized in that the eccentric drive mechanism (34) is composed by a rotating eccentric (51, 52) which is slideable nested in a milled recess (5) in the swing arm (10), and that the eccentric (51, 52) is driven by the twisting motor (5) via a transmission shaft (54) connecting the twisting motor re- duction gear drive (6) with the eccentric (51, 52), and that the swing arm (10) is mounted pivotable on the through-going spring shaft (2) with its pivoting axis coincident with the center axis (25) of this shaft (2).

8. A starting device according to claim 1, characterized in

- a first system of non-contacting electronic sensors, such as inductive sensors or photocells, located next to the flywheel ring gear (17) for detecting the exact position of the ring gear teeth when the engine is stationary,

- an second sensor system located next to the pinion gear wheel (12) composed of non-contacting electronic sensors such as photocells or encoders with the object to continuously recording the position of the teeth of the pinion gear wheel (12), and

- a electronic control system, e.g. based on an electronic microprocessor, including a program to control the twisting motor (5) on the basic on the records received from the different sensors in order to stop the twisting motor (5) after completed tensioning the torsion spring (4) in a parking position, where exact match between the teeth on the flywheel ring gear (17) and the teeth on the pinion gear wheel (12) is obtained, i.e. so that the pinion gear wheel (12) is ready to slide into engagement with the ring gear (17) without any correction or resistance.

9. A starting device according to claim 1, characterized in that the ratchet (11) is provided with a direct-acting, separate electromagnet (32) with the object to release the ratchet (11), or that the ratchet is under direct or indirect influence of the electromagnet (15), which has the object to push the pinion gear wheel (12) into start position in engagement with the ring gear (17), and in such a way, that the starting device is in any event first triggered, when the fully engagement between the two sets of teeth (12 and 17) is obtained.

10. A starting device according to claim 1, characterized in that the starting device comprises a back- stop (7) which is built-in as an integral part of the twisting motor reduction gear drive (6), or alternatively there is mounted a second ratchet wheel which is inserted on the through-going spring shaft (2) and is rotatable fixedly connected with the torsion gearwheel (8), which ratchet wheel create a backstop for the twisting motor and to this purpose is provided with a spring-loaded ratchet with a locking direction oppose the twisting direction.