EP0569951B1 - Starter device for internal combustion engines - Google Patents

Description

• einen Elektromotor als Startermotor
• ein Untersetzungsgetriebe zur Reduzierung der Startdrehzahl
• eine Zwischenwelle mit einem Steilgewinde
• ein Ritzel, dessen Innendurchmesser ein Gegen-Steilgewinde aufweist, welches mit dem Steilgewinde der Zwischenwelle zusammenarbeitet
• einen Zahnkranz am Außendurchmesser des Schwungrads des zu startenden Verbrennungsmotors, in welchen das Ritzel der Zwischenwelle beim Startvorgang einspurt,

wobei in einer Zahnradgetriebe-Baugruppe, die durch das Einspuren des Ritzels zustande kommt, im Kraftflußweg zwischen dem Elektromotor und dem Schwungrad ein drehelastisches Glied angeordnet ist.The invention relates to a starting device for internal combustion engines, especially for smaller single-cylinder units. Such a starting device includes

• an electric motor as a starter motor
• a reduction gear to reduce the starting speed
• an intermediate shaft with a high helix thread
• a pinion, the inner diameter of which has a counter helical thread, which cooperates with the helical thread of the intermediate shaft
• a ring gear on the outer diameter of the flywheel of the internal combustion engine to be started, into which the pinion of the intermediate shaft meshes during the starting process,

a torsionally elastic member is arranged in a gear transmission assembly, which is caused by the engagement of the pinion, in the power flow path between the electric motor and the flywheel.

The invention further relates to a method for starting a Internal combustion engine, in particular a one-cylinder internal combustion engine with the help of an electric motor, in which the electric motor and any subsequent ones in a rigid angular relationship Gear parts are rotated before one effective connection with the crankshaft becomes.

Single-stage thrust starters are the rule for car and truck engines; Motorcycle engines have this type of start only occasionally on. There are also electric motors via chain drives with the Crankshaft of the engine to be started with interposition an overrunning clutch to add weight and space save up. But mostly it is with the pinions and Chain drives around single-stage reduction gears. The thrust drive usually includes a magnetic switch that the small pinion connected to the starter motor in the tooth mesh with the flywheel teeth before the engine is energized. Screw drives can also be used without engagement systems be designed, the moment of inertia of the single-pinion with the correct design of its bearing in a steep thread on the driving shaft with its rapid increase in speed First mesh axially and only when the axial limit is reached Transmits torque.

All such systems use relatively large motors, the Torque is designed so that the compression generated Resistance can be overcome in every operating case.

JP-A-60 166 754 is according to the Patent Abstracts of Japan (European Patent Office) a starting device for internal combustion engines known, the one on an output shaft of a Starter motor attached tubular torque damper which torque damper rotates the output shaft of the starter motor on a coaxial on the starter shaft Bearing drive pinion of a gear reduction arrangement transmits. The gear reduction arrangement also has two to an intermediate shaft on coaxial gears, of which the one meshes with the drive pinion and the other during the starting process apparently with a gear integral with the crankshaft can be brought into mesh. The torque damper is included a tubular, torsionally elastic rubber buffer element, that can be turned and compressed for torque buffering is deformable.

For the purpose of saving weight, it has the invention task, much smaller and therefore high-revving Electric motors from other areas of application for electric start of small combustion engines. Costs and installation space should be kept small.

Another object of the invention is to provide a starting device whose electric motor is better than when stationary the technology against hard torque surges in the event of blockages the crankshaft is protected.

According to the invention, at least one of these tasks is solved proposed for the starting device mentioned at the beginning, that the torsionally elastic member consists of a mainspring, the as a spring accumulator between the intermediate shaft and one on it mounted gear is arranged, the mainspring for Limitation of the torque with an inner spring end form-fitting with the intermediate shaft and with the outer spring end is frictionally connected to the gear. For the beginning mentioned method is proposed according to the invention, a to use the starting device according to the invention.

A great advantage of the invention is that now a Electric motor can be used, which is also taking into account any reduction or not under is sufficient in all circumstances to avoid a problem occurring on the crankshaft To overcome the starting moment. The entrainment effect between the electric motor and the crankshaft is increasing Winding deformation and thus increasing torque transmission capacity the in the power flow path between the electric motor and the crankshaft arranged mainspring made so that the electric motor initially without this winding deformation substantial rotation of the crankshaft can run up to by the speed reached by the electric motor and that of it downstream if necessary in a rigid angle of rotation relationship Kinetic energy built up in transmission parts is sufficient to achieve this To overcome the crankshaft starting torque.

This mode of operation differs from the mode of operation the starting device known from JP-A-60 166 754, that thanks to the use of a windable mainspring as Starter motor used electric motor when starting much larger turning distance up to the start of taking the Crankshaft is available, so that despite low performance of the electric motor by building an enlarged kinetic Energy reliable starting the internal combustion engine is made possible.

Compared to the known starting device according to JP-A-60 166 754 the advantage is also achieved that in the event of a blockage the crankshaft, for whatever reasons is a hard torque surge on the electric motor is avoided. Smaller electric motors are one such a hard torque surge not easily grown.

There are advantages in terms of cost and weight at solution according to the invention through the use of electric motors, that for toys or in motor vehicles to operate serve the various tax movements. Such small engines are manufactured in large numbers and stand out due to a favorable power-to-weight ratio and small installation space out. You can when paired with the flywheel Motor interact via a drive spring according to the invention, certainly for a smaller one comparable to the starting torque of the engine Starting torque must be designed as the mainspring as a spring accumulator the first compression stroke with the help of tensioning the motive time slowly overcomes and then one over the starting speed of the starter motor causes the flywheel to spin beyond it, which leads to reliable starting of the engine.

During the first rotation, the mainspring also "smoothes" the non-uniformity of the rotary movements in particular Single cylinder engines. Therefore, there are also advantages in the design to recognize the flywheel mass of the flywheel, because the the first revolutions during the starting process partially takes over the tasks of the flywheel. The first Rotation of the internal combustion engine is caused by the mainspring distributed a larger rotation range of the starter motor.

A single-track device without freewheel and engagement device, thus a tooth mesh aimed purely at angular acceleration, is immediately spurted out, i.e. disengaged when the driven flywheel overtakes and the transmitted one Torque goes to zero. Becomes a rigid drive without elastic member used, so there is already after the first Ignition this danger because of the inertia of the armature mass of the electric motor cannot accelerate accordingly quickly.

The spiral-shaped mainspring lies in that for them provided annular space of a gear on the outside only, while being positively connected to the shaft inside is. The spring generates in its rest position by its bias on its outer diameter a frictional engagement, the Limit torque slightly exceeds the starting torque. On the engine side Blockages, reverse ignition or The spring is initially like this around the shaft wrapped until the external frictional engagement is reduced and the elastic shaft connection slips.

Finally, the design with an intermediate shaft has the advantage on that space remains coaxial with the flywheel Housing, for example, a manual starter.

Preferred developments of the starting device according to the invention are specified in the subclaims 2 - 8, the further Advantages.

Fig. 1

eine Starteinrichtung mit Elektromotor, Zwischenwelle und Schwungrad des teilweise dargestellten Verbrennungsmotors;

Fig. 2

eine Triebfeder in einer spiralenförmig gewickelten Ausführung;

Fig. 3

die Triebfeder im Schnitt in ihrem Einbauzustand in einen Zahnrad.

The invention is explained below with reference to drawings of an embodiment. Show it

Fig. 1

a starting device with an electric motor, intermediate shaft and flywheel of the partially illustrated internal combustion engine;

Fig. 2

a mainspring in a spiral wound design;

Fig. 3

the mainspring in its installed state in a gear.

If 1 is a motor housing of the internal combustion engine to be started a crankshaft 2 is mounted in it, at the free end of a flywheel 3 is rotatably arranged. This flywheel 3 has a ring gear on its outer circumference 4, which is preferably in one piece with the flywheel 3 connected is. engages in the toothing of this ring gear 4 the teeth 6 of a pinion 5, which by means of a Steep thread 7 rotatable and helical on an intermediate shaft 8 is axially displaceable. An axial compression spring 5a has the task of the pinion 5 only in its rest position to hold on; in the function of the on rotating mass of the pinion 5 based one-track mechanics does not engage this spring 5. The intermediate shaft 8 is rotatable in a bearing 10 in the housing stored and carries a bearing bush at the opposite end 19, which rotatably supports a gear 11 on the intermediate shaft 8. The end of the intermediate shaft 8 has a positive entrainment - here in the form of a double flat 8a - which has an inner Spring end 18a of the previously described mainspring 18 - here is positively connected via a driver 17.

The spiral spring lies with the majority in the relaxed state their turns and finally with its outer spring end 18b in a cylindrical recess of a gear 11 and creates a frictional connection for the next starting process. The gear 11 is finally with its teeth 12 the toothing 13 of a drive pinion 14 in continuous engagement, which rotatably with a starter shaft 16 of an electric motor 15 is connected.

The rotary movements coupled by the mainspring 18 between Electric motor 15 and flywheel 3 require damping in order not Vibrations occur, both the frictional engagement of the Drive spring 18 in its outer bearing in the gear 11 prematurely solve, as well as the premature disengagement process of the pinion 5 could initiate. This damping consists in a space-saving attached disc 21, which is rotatably on the intermediate shaft 8 is arranged on the double 8a and one their outer circumference lying by the force of a Spring 22 is pressed against the gear 11.

Coaxial to the flywheel 3 is one in our embodiment Hand starting device 23 arranged in the form of a pull starter 24, the directly on the flywheel 3 in a known manner works.

It was still on the advantage of one with a torsionally flexible Link 20 equipped starting device pointed out: The gearing 6 of the pinion 5 tracks "soft" into the ring gear 4, i.e. there are no hard impacts when the teeth meet on how it is known from thrust starters, where it is sometimes There is damage to the end faces of the teeth. Rather leaves the torsionally elastic member 20 a short time when touching the tooth Delay of the meshing process until the subsequent tooth gap is found. It is therefore also possible to use gears in Integrate flywheels that are designed as pole wheels and therefore be made of electrically non-conductive aluminum material have to.

The basic mode of operation of the starting device according to the invention can also be summarized as follows will:

Before the start there is the pinion 5 with its teeth 6 out of engagement with the ring gear 4 of the flywheel 3. All parts of FIG. 1 are initially at a standstill. This will the electric motor 15 is connected to the power supply, which is formed in particular by the battery of the vehicle can be. The rotor of the motor 15 starts rotating. With the drive pinion 14 rotates. This drive pinion 14 drives according to the number of teeth ratio between the number of teeth of the teeth 13 of the drive pinion 14 and the number of teeth of the toothing 12 of the gear 11 this latter gear 11 at a lower speed on. The gear 11 takes over the spiral drive spring 18 and the driver 17, the intermediate shaft 8 in the direction of the arrow 30 of Fig. 2 with. The entrainment effect is based on the one hand on the frictional engagement between the outer spring end 18b and the inner peripheral surface 11i of the Gear 11 and on the other hand on the at least one Direction of positive engagement of the inner spring end 18a in the driver 17. By the engagement of the high helix thread 7 the intermediate shaft 8 and the corresponding inner part thread 6a of the pinion 6 there is a tendency to take it along the pinion 6 through the intermediate shaft 8. This tendency but now counteracts the moment of inertia of the pinion 5. The pinion 5 tries to take it through the intermediate shaft 8 to escape, thanks to the corresponding slope of the intermeshing steep teeth 7 and 6a on the Bolted intermediate shaft 8 to the right, against the Effect of the helical compression spring 5a. With this screw connection of the pinion 5 to the right, the teeth 6 of the Pinion 5 in engagement with the ring gear 4 of the flywheel 3.

The engagement of the toothing 6 in the ring gear 4 can done essentially bumpless. If namely the gearing 6 with the axially directed tooth ends against the axially directed tooth ends of the ring gear 4 butts, so the right-hand movement of pinion 5 briefly interrupted, until there are gaps and teeth of the gearing 6 and the ring gear 4 in a further displacement axially to the right of the pinion 5 face each other. Then the pinion 5 can continue move right and in full engagement with sufficient axial overlap with the ring gear 4 of the flywheel 3 to step. Only now can the flywheel 3 start rotating from the rotor 15a of the motor 15 the output shaft 16, the drive pinion 14, the gear 11, the mainspring 18, the intermediate shaft 8, the helical thread 7 and 6a and the pinion 6. At this stage of the starting process becomes the mainspring 18 against elastic resistance deformed so that their turns are from the radially innermost Progressing turn towards the radially outer turns close around the driver 17. This deformation of the Mainspring 18 begins when the crankshaft 2 is approximately in the Course of a compression stroke of one assigned to it Piston with respect to the associated cylinder a resistance to rotation experiences d. H. only against increasing torsional resistance can be taken.

It can be seen that the speed of the Rotor 15a of the electric motor 15 initially considerably can be increased until that of a compression stroke Resistance against the crankshaft turning 2 occurs. The acceleration of the rotor 15a can be partial take place in the period until the pinion 6 in the Has engaged ring gear 4. Then there is another Acceleration is also conceivable until the flywheel 3 has reached an angular position in which of the Piston forth resistance to further twisting occurs. After all, there is another acceleration conceivable in the initial phase of winding the mainspring 18 on the driver 17. Thus, the runner 15a and get with it the gear 11 and those with the gear for common rotation connected parts increased speeds, being a kinetic Energy is built up, which is composed of the kinetic energy of the individual rotating parts, so for example, the rotor 15a, the pinion 14 and the Gear 11. The kinetic energy of this individual Parts is by the respective speed of these parts and determines the respective moment of inertia of these parts. This kinetic energy is now to overcome the rotational resistance of the crankshaft 2 is available, that of the associated piston cylinder pair or more such pairs of piston cylinders abuts against the crankshaft 2 and must be overcome to start.

If the mainspring 18 around the driver 17 in the direction of the arrow 30 of FIG. 2 winds up, so does the other Winding counteracting internal torsional moment of the mainspring 18 on. This increasing torsional moment is available Torque transmission from the gear 11 forth on the intermediate shaft 8 and therefore also for further torque transmission available on crankshaft 2. If the inside Torsional moment of the drive spring 18 is equal to that on the crankshaft 2 applied rotation resistance, so the crankshaft 2 are taken against this rotational resistance, and for this take-along now stands the previously built one kinetic energy available. From this kinetic Therefore, energy originates to overcome the rotational resistance on the crankshaft 2 a possibly essential greater torque available than the engine 15 could muster. Therefore the crankshaft 2 is turned, and the associated internal combustion engine can after Go through the first or another ignition point. So a starting process is achieved, although the Electric motor 15 not, or at least not among all Operating conditions are sufficient to the crankshaft 2 to overcome occurring rotational resistance.

It is of particular advantage that the to spin the crankshaft 2 does not build up kinetic energy is suddenly transferred to the crankshaft, but via the elastically flexible mainspring 18.

One can by appropriate choice and dimensioning of the Components involved in the startup process ensure that the Drive pinion 14 make a plurality of revolutions can before the crankshaft 2 is rotated. In this way, even with small dimensions, this Components have sufficient energy or in other words sufficient angular momentum is made available, around the crankshaft 2 under all conceivable operating circumstances to crank and thus the internal combustion engine to start up bring to.

It is also readily apparent that the choice of one Coil spring as the mainspring only as an embodiment is to be understood. Basically there are also other torsion springs between the gear 11 and the driver 17th conceivable.

However, there is a particular advantage of the spiral spring in that they are easily in frictional connection with the Gear 11 can be brought by contacting the Inner circumferential surface 11i of the gear 11 creates. At this Then there is an overload clutch for the case on the motor side Blocking, reverse ignition, and Like. Available.

The one described above, based solely on the moment of inertia of the pinion 5 based displacement of the pinion 5 in engagement with the ring gear 4 also only adjusts preferred embodiment. It is straightforward recognizable that you can rotate the pinion 5 with the Intermediate shaft 8 could also inhibit that one Pinion 5 or one with the pinion 5 for common rotation fixed part can attack a friction brake, which alone or in support of the moment of inertia of the pinion 5 effect the entrainment of Inhibit pinion 5 through the intermediate shaft 8 and thus the Axial displacement of the pinion 5 for engagement with the ring gear 4 could initiate.

It is also readily apparent that the shift the pinion 5 in its engagement position with the ring gear 4th could also be externally controlled, for example by means of an electromagnet, which is dependent on that by the rotor 15a speed reached the coupling of the teeth 6 with the Gear ring 4 causes. In such a case, however, would be the basic idea of the invention realizes that one small electric motor with low torque to overcome a larger starting torque on crankshaft 2, by the rotor of the motor and that rotor gearbox-connected gearbox elements until construction a predetermined kinetic energy run up and this kinetic energy then via torsion suspension attaches to the crankshaft for starting.

Claims (9)

1. Starting device for internal-combustion engines, in particular for relatively small single-cylinder units, comprising

   an electric motor (15) as starter motor

   a reduction gear (13, 11) for reducing the starting speed

   an intermediate shaft (8) with a steep-lead-angle thread (7)

   a pinion (5) of which the internal diameter has a counter-steep-lead-angle thread (6a) cooperating with the steep-lead-angle thread (7) of the intermediate shaft (8)

   a ring gear (4) on the external diameter of the flywheel (3) of the internal-combustion engine (1) to be started, in which the pinion (5) of the intermediate shaft (8) engages during the starting process,

   wherein a torsionally elastic element (20) is arranged in a gear module, formed by the meshing of the pinion (5), in the power flux path between the electric motor (15) and the flywheel (3), characterized in that the torsionally elastic element (20) consists of a rotationally driving spring (18) which is arranged as a spring-energy store between the intermediate shaft (8) and a gear-wheel (11) mounted thereon, wherein the rotationally driving spring (18) is connected by an inner spring end (18a) positively to the intermediate shaft (8) and by the outer spring end (18b) non-positively to the gear-wheel (11), to limit the torque.
2. Starting device according to claim 1, characterized in that the design and adaptation of the rotationally driving spring (18) allows a plurality of rotations of the driving pinion (14) before the flywheel (3) begins to rotate.
3. Starting device according to claim 1 or 2, characterized by a design which is such that, during the starting process, once the teeth (6) of the pinion (5) have meshed in the ring gear (4) of the flywheel (3), the pinion (5) has reliably adopted its working position and has come to a standstill there, the actual starting process begins with rotation of the flywheel (3) only after the clockwork spring (18) has been tensioned.
4. Starting device according to one of claims 1 to 3, characterized in that the rotationally driving spring (18) is allocated a damping element which produces forces counter to the rotational movement of the gear-wheel (11) on the intermediate shaft (8).
5. Starting device according to claim 4, characterized in that the damping element consists of a disc (21) which is pressed axially against the windings of the rotationally driving spring (18) by a spring (22).
6. Starting device according to one of claims 1 to 5, characterized in that the intermediate shaft (8) is spatially so far removed from the crankshaft (2) that a manually operated starting device (23) can be arranged in a casing (9) coaxially to the crankshaft (2).
7. Starting device according to one of claims 1 to 6, characterized in that the electric motor (15), the intermediate shaft (8) with the elastic element (20) and optionally the manually operated starting device (23) are arranged in a casing (9).
8. Starting device according to one of claims 1 to 7, characterized in that the rotationally driving spring is a spiral spring (18).
9. Method of starting an internal-combustion engine, in particular a single cylinder internal-combustion engine by means of an electric motor in which the electric motor (15) and any gear parts (14, 11) following it in a rigid angular relationship are set into rotation before an entraining connection to the crankshaft (2) is produced, characterized by the use of a starting device according to one of claims 1 to 8, in particular for application of an electric motor (15) which is not adequate or not adequate under all circumstances to overcome a starting torque occurring on the crankshaft (2), even when making allowances for a reduction.

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