EP2290222B1 - Starter device for combustion engine - Google Patents

Description

Technical area

The invention relates to a starting device for at least one internal combustion engine, in particular cable start device for at least a two-stroke or four-stroke engine, with at least one rotatably mounted in a housing pulley or cable drum for generating a driving torque for a motor shaft by means of at least one Anwerfergriffs or pull handle on at least one force transmission means, in particular via a starter cable or traction cable, in rotation and at least one elastic coupling member with at least one driver member, in particular with at least one pawl, connected by means of which the drive torque is transferable to the motor shaft, the coupling member has two ends, wherein one end engages with the driver member and another end engages the sheave or drum.

State of the art

Such a starting device is for example from the DE 203 01 182 U1 as well as the DE 203 19 902 U1 known. In the starting devices described therein, it is always necessary that good cooling of the internal combustion engine can take place with a cooling air flow leading to a fan through the starting device.

The starting device, as described in the two documents mentioned above, is housed in a housing in front of the internal combustion engine. The internal combustion engine is cooled by means of the air passing through the starting device. The ventilation elements of the housing, such as ventilation slots, allow the entry of a cooling air flow in a fan arranged behind the starter for cooling the internal combustion engine. Frequently, however, in such devices, the cooling air flow is shielded from the housing to the engine by elements of the starting device, or the cooling air flow disturbed by the elements of the starting device.

Since such Stailvorrichtungen are often used in devices such as chainsaws, which are exposed to high loads, the best possible cooling of the internal combustion engine is desirable.

Furthermore, from the EP 1 396 060 A2 a cable start device for an internal combustion engine known. Again, the same arrangement of the starter device as described in the above-described prior art.

The US 4,480,605 shows a starting device for an internal combustion engine, which is designed with a rotatably mounted in a housing sheave, which is set for generating a driving torque for a motor shaft by means of an access via a pull rope in rotation.

In the EP 1 712 779 A2 a starting device for an internal combustion engine is shown with features that the coupling member is formed by a coil spring, but which is wound in a plane.

The US 2,772,669 shows a starting device for an internal combustion engine, but no elastic coupling member is provided in the form of a spring.

The EP 1 484 499 A2 shows a starting device for an internal combustion engine, wherein the coupling member is designed as a cylindrically wound coil spring.

DESCRIPTION OF THE INVENTION: Problem, Solution, Advantages

The invention has for its object to achieve a better cooling of the internal combustion engine at a starting device of the type mentioned.

This object is achieved by the feature combination specified in claim 1.

According to the teachings of the present invention, the coupling element is now designed as a wire-wound spring with decreasing cross-sectional areas whose tapered shape follows the inflowing cooling air flow of the ventilation elements of the housing.

Under cross-sectional area here is not the cross-sectional area of the spring wire, but the area enclosed by a spring coil surface.

With an embodiment according to the invention, a significantly improved cooling of the internal combustion engine downstream of the starter is achieved, since the cooling air inflow is improved in the fan arranged behind the starter and thus a good flow of a blade-carrying fan can be achieved.

In addition, the inventive design of the starter device combines the advantage of not acting cooling air flow with the advantage of being sufficiently dimensioned by the spring force for the application.

Another advantage of using a spring wound from wire, whose cross-sectional areas is substantially smaller from one to the other end, that the space required in the starter is lower.

A spring having a uniform cross section of the largest cross section of the spring would be sufficient of the spring force in a starter system according to the invention, but would hinder the incoming cooling air flow and therefore lead to a poorer cooling of the internal combustion engine.

Advantageous embodiments of the invention are characterized in the subclaims.

It is according to the present invention not necessary that the spring is formed in a circular shape and thus as a truncated cone. Rather, all possible wound forms with tapered cut surfaces, such as truncated pyramids, Tetraederstümpfe, etc. conceivable. Likewise, a truncated cone shape with elliptical cross-sectional areas or a truncated pyramidal shape with polygonal cross-sectional areas would be conceivable.

According to a preferred embodiment, the wound spring is a tapered coil spring. Such coil springs are commercially available well and inexpensively.

According to a preferred embodiment, the spring is also designed so that the spring has a progressive spring characteristic. For example, when the spring is loaded, it is possible to first make use of the larger turns and let them "go to block" in order then to make use of the smaller turns using the progression. Such a progressive spring characteristic harmonizes very well with the flow of forces in the starting device. The torque to be applied to the motor shaft during the starting process is subject to considerable fluctuations, since in the compression phase of the piston up to top dead center, a very high torque is to be applied, while in the expansion phase the applied torque decreases.

Particularly good progression properties of the spring can be achieved if the ratio of diameter or longitudinal blade on a base surface and a top surface of the spring is 0.9 or less, preferably 0.8 to 0.6 and particularly preferably about 0.73.

Preferably, the wire diameter of the spring is in the range of 2 to 4 mm and, according to a further preferred embodiment, 2.5 to 3.5 mm. According to A particularly preferred embodiment provides that the wire diameter is about 2.8 mm.

The wire of the spring could have all other conceivable cross-sectional shapes, such as a round, an oval, a square and / or a triangular cross-section.

As a material for the spring while a commercial spring steel will be used. It would also be conceivable, however, that a copper-tin alloy is used. The material could also have a coating beyond.

Brief description of the drawings

• Fig. 1 eine schematische Explosionsdarstellung einer Startvorrichtung gemäß des Standes der Technik;
• Fig. 2 eine schematische Explosionsdarstellung einer Startvorrichtung gemäß einer bevorzugten Ausführungsform und des Verbrennungsmotors sowie Teile der Vorrichtung, in die diese eingesetzt werden;
• Fig. 3 eine schematische Darstellung einer Vorrichtung gemäß der in Fig. 2 gezeigten Ausführungsform mit Elementen im eingebauten Zustand; und
• Fig. 4 eine schematische Schnittdarstellung dreier Möglichkeiten der um einen Lagerzapfen gewickelten Spiralfeder.

An embodiment of the invention will be explained below with reference to the drawing. It show here

• Fig. 1 a schematic exploded view of a starting device according to the prior art;
• Fig. 2 a schematic exploded view of a starting device according to a preferred embodiment and the internal combustion engine and parts of the device in which they are used;
• Fig. 3 a schematic representation of a device according to the in Fig. 2 embodiment shown with elements in the installed state; and
• Fig. 4 a schematic sectional view of three possibilities of wound around a journal coil spring.

Preferred embodiment of the invention

In the representation of the prior art and the embodiment shown, the corresponding elements are designated by the same reference numerals, wherein the reference numerals of the prior art are provided with an apostrophe.

In Fig. 1 there is shown a starting device 100 'as known in the art. Such a starting device 100 'is, as well as in Fig. 2 and 3 illustrated starting device 100 for manually starting an internal combustion engine determines, for example, belongs to a motor chain saw. The cable start device 100, 100 'is accommodated in a housing 10, 10' which is suitable for both the embodiment according to the prior art (US Pat. Fig. 1 ) as well as shown Embodiment of the invention ( Fig. 2 and 3 ) is a removable with louvers 11,11 'provided cover of the motor housing, in which inter alia, an air guide 12 is integrated and an adjacent pole 13th From the inner wall of the housing 10,10' goes out a bearing pin 14 '(only in Fig. 1 visible), which is surrounded by a likewise substantially housing-fixed spring housing 15,15 'for a spiral, on the edge of the spring housing 15,15' on one side clamped starter spring 16,16 '. This starter spring 16,16 'serves as a return spring for the pulley or cable drum 17,17'.

The pulley or cable drum 17,17 'has a rear pin 18 (see Fig. 2 ) which projects through a central bore of the spring housing 15,15 'in this and has an axial slot for the engagement of the inner end of the spiral-shaped starter spring 16,16'.

On the pulley or cable drum 17,17 'is as Kraftübertragungsmittel a starter rope or pull rope (not shown) wound, the free end of the housing 10,10' out and attached to a handle. By pulling on the starter rope by means of the handle, the sheave or rope drum 17, 17 'is set in motion by handling the starter rope or pulling rope around the bearing pin 14'.

The pulley or cable drum 17,17 'has a bearing pin 14' surrounding annular receiving space 20 ', which is limited to the starter spring 16/16' out of the end wall 21. Between this end wall 21 of the pulley or cable drum 17,17 'and a receiving space 24 of a ratchet member 25,25' is a coil spring 26,26 'arranged.

The outer, that is, the end wall 21 of the pulley or cable drum 17,17 'facing the end of the coil spring 26,26' is mounted in a slot 27 ', which is provided in an annular shoulder of the end wall 21. This shoulder encloses the coil spring 26,26 ', the outer winding rests against the inner wall of the paragraph. The Klinkenmitnehmerglied 25,25 'facing the end of the coil spring 26,26' is mounted in the pawl Mitnehmermitnehmerglied 25,25 '.

In the mounted state of the starting device 100 passes through the housing-fixed bearing pin 14 'has a central bore of the end wall of the pulley or cable drum 17,17', so that this central bore forms a bush-shaped receptacle for the bearing pin 14 '. In an axial internal thread of the journal 14 'a fastening screw 28' is screwed, the head of the Klinkenmitnehmerglied 25,25 'is fixed.

When the sheave or rope drum 17,17 'is rotated by pulling on the starter rope or pull rope, the sheave or rope drum 17,17' via the coil spring 26,26 'the Klinkenmitnehmerglied 25,25' with. By means of this ratchet Mitnehmergliedes 25,25 'so the rotational movement of the pulley or cable drum 17,17' and thus the torque on the driven motor shaft übertragb ar.

The coil spring 26 ', as in Fig.1 is shown according to the prior art, represents a cylindrical coil spring and thus is also the Klinkenmitnehmerglied 25 'formed accordingly.

Unlike in Fig. 1 illustrated embodiment according to the prior art, the coil spring 26 in the Fig. 2 and 3 formed according to a preferred embodiment of the present invention as a truncated cone, the base surface of the pulley or cable drum 17 faces, while the top surface facing the Klinkenmitnehmerglied 25.

Such a designed coil spring 26 leads to a significantly improved ventilation behavior of the internal combustion engine, since the inflow of the cooling air is improved by the starting device 100 in the arranged after the starting device air guide 12, since the conical spring 26 follows the incoming cooling air flow, and thus the cooling air flow leads positively ,

In addition, when driving or rotating the motor shaft, in principle, the compression in the internal combustion engine increases up to its dead center position of the piston and then drops again; Correspondingly, the reaction torque fluctuates periodically, which in the case of a conventional starting device has the effect of high force peaks which must be applied during starting. To compensate for the coupling element and here according to the embodiment shown, a coil spring 26,26 'is provided.

According to the embodiment of the prior art, the coil spring 26 'is dimensioned so that the Klinkenmitnehmerglied 25' with the speed of the pulley or cable drum 17 'is taken as long as the reaction torque of the motor shaft remains below a predetermined limit, wherein the piston of the engine in the areas in front of and behind the dead center. As the reaction torque increases beyond this limit, the coil spring 26 'deforms by contracting its turns, so that the rotational speed of the pawl driver member 25' decreases, while the pulley or cable drum 17 'can be further rotated at the same speed and with only moderately increasing force.

According to the in the Fig. 2 and 3 Shown embodiment, a coil spring 26 is now used, in which the diameter ratio of top surface to bottom surface is about 0.73. Furthermore, a wire was used for the coil spring with a diameter of about 2.8 mm.

In such an embodiment of the invention, the spring develops a progressive spring characteristic. It is therefore not, as described above, when a limit value is exceeded, the coil spring 26 is deformed directly, but it is possible first to let go the larger turns on block to then take advantage of a progression to use the smaller turns of the coil spring 26, so that too Here, the rotational speed of the pawl Mitnehmermitnehmerglieds 25 decreases, while the pulley or cable drum 17 can be further rotated at the same speed and with only moderately increasing force.

In the Fig. 4 is a section of a device according to the invention shown and that a bearing pin 14 on which a coil spring 26 is located. The FIGS. 4a), 4b ) and 4c ) show various embodiments of the shape of the journal, resulting in different spring characteristics. The in the Fig. 4a ) shown embodiment shows a conical spiral spring 26 which is arranged around a cylindrical bearing journal. Such an embodiment leads to a linear spring characteristic.

The embodiment that is in Fig. 4b ) is shown, shows a conical coil spring 26 which is disposed about a bearing pin 14, which is one of the coil spring 26th corresponding cone angle. Such a design leads to a degressive spring characteristic.

The Fig. 4c ) shows a conical coil spring 26 which is disposed about a conical bearing pin 14 whose cone falls more than the cone of the coil spring 26 and thus has a progressive spring characteristic result.

reference numeral

100/100 '

starter

10/10 '

casing

11/11 '

vents

12

air duct

13

flywheel

14/14 '

pivot

15/15 '

spring housing

16/16 '

starter spring

17/17 '

Pulley or rope drum

18

Spigot of pulley or rope drum

19

axial slot

20 '

Reception room of the pulley or rope drum

21/21 '

Front wall of the pulley or rope drum

24

Reception room of a latch driver member

25/25 '

pawl driver

26/26 '

spiral spring

27 '

Slot in the end wall 21/21 '

28 '

fixing screw

Claims (10)

1. A starting device (100) for an internal combustion engine, having a cable sheave (17) rotatably mounted in a housing (10), which can be set rotating to generate a drive torque for an engine shaft by means of a pull handle via a pull cable and is connected via an elastic coupling element (26) to a driver element (25) and by means of which the drive torque can be transmitted to the engine shaft, wherein the coupling element (26) has two ends, wherein one end is in engagement with the driver element (25) and another end is in engagement with the cable sheave (17),
   characterised in that the coupling element (26) has a three-dimensional spring (26) wound from wire, the cross-sectional areas of which diminish from the end facing the cable sheave (17) towards the end facing the driver element (25).
2. The starting device according to claim 1, characterised in that the wound spring (26) has a truncated-cone shape with round and/or elliptical cross-sectional areas or a truncated-pyramid shape with rectangular or polygonal cross-sectional areas.
3. The starting device according to one of the preceding claims, characterised in that the wound spring (26) is a tapering spiral spring.
4. The starting device according to one of the preceding claims, characterised in that the spring (26) has a progressive characteristic.
5. The starting device according to one of the preceding claims, characterised in that the ratio of diameters at a base area and a top area of the wound spring (26) is 0.9 or less.
6. The starting device according to one of the preceding claims, characterised in that the ratio of the diameters lies in the range from 0.8 to 0.6 and is preferably approximately 0.73.
7. The starting device according to one of the preceding claims, characterised in that a wire diameter of the spring (26) lies in the range from 2 to 4 mm and is preferably 2.5 to 3.5 mm.
8. The starting device according to claim 1, characterised in that the wire diameter of the spring (26) is approximately 2.8 mm.
9. The starting device according to one of the preceding claims, characterised in that the wire of the spring (26) has a round, an oval, a rectangular and/or a triangular cross section.
10. The starting device according to one of the preceding claims, characterised in that the extent of the spring (26) from the end facing the cable sheave (17) to the end facing the driver element (25) lies in the range of smaller than 10 mm, preferably 7.25 mm.

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