EP2299104B1 - 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, which generates a drive torque for a motor shaft by means of at least one Anwerfergriffs or pull handle at least one force transmission means, in particular via a starter rope 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 is engaged with the cam member.

The operation of a starting device for an internal combustion engine, in particular a cable starter for an internal combustion engine, in particular for a two-stroke or four-stroke engine, often caused problems in the past, because at startup by the compression in the engine periodically high reaction forces occur, whereby changing and passing very high forces act on the hand of the operator.

State of the art

To reduce the transmission of these particularly strong, caused by the compression in the engine reaction forces on the handle of the starting device and thereby facilitate the starting process is, for example, in the DE 41 35 405 proposed to cushion the fluctuations of the applied torque to the motor shaft elastically.

For this purpose, between the power transmission means, in particular the Anwerferseil or pull rope, the handle associated pulley or cable drum and the driver member, in particular the jack driver, the crankshaft an elastic member interposed, by means of which the handle and power transmission means mediated train movement during startup of the above-mentioned fluctuations is somewhat or completely freed.

In such, known from the prior art starting device, the spring force of the coupling element acts on the pulley or cable drum, so that it must be robust and thus made heavy.

From the DE 10 2008 007 291 A1 a starting device for an internal combustion engine is known. This has an actuating device and a driver, which can be coupled via coupling means with the crankshaft of the internal combustion engine. The driver and the actuator are rotatably mounted about a rotation axis. The driver and the actuator are connected to each other via a damping spring, which is connected to a first end with the actuator and with a second end to the driver.

The EP 1 712 779 A2 shows a starting device for an internal combustion engine. It can be seen that a pull rope is wound on a pulley. The sheave is operatively connected to a coupling member, and the coupling member has an end connected to a cam member, and the coupling member has another end which is fixed in an opening of the sheave. Here, the pull rope is fixed in an opening.

The DE 10 2007 008 327 A 1 shows a starting device for an internal combustion engine in which a pull rope is wound on a pulley. The sheave is operatively connected to a coupling member, and the coupling member has an end connected to a dog member. In particular, the coupling member is attached via one end to a pin of the sheave, so that an operative connection between the coupling member and the pull rope also does not exist directly.

The US 4,480,605 shows a starting device for an internal combustion engine with a pulley on which a pull rope is wound, and the pulley is engaged with a driver member, without an elastic coupling member would be located between pulley and driver member. A spiral spring serves only as a return spring.

The US 2,772,699 shows a starting device for an internal combustion engine, which has no elastic coupling member which would be in engagement with the end of the pull rope, which pull rope would be passed through the pulley.

DESCRIPTION OF THE INVENTION: Problem, Solution, Advantages

The invention is based on the object to make a starting device of the type mentioned by direct operative connection of power transmission means and elastic member / coupling member as easy as possible.

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

In a starting device according to the invention for at least one internal combustion engine is now an elastic coupling member with at least one driver member, in particular with at least one jack driver, connected by means of which the drive torque is transferable to the motor shaft. The coupling member has two ends, one end of which is in engagement with the driver member and another end of the coupling member is engaged with the sheave or cable drum and the power transmission means.

In such a starting device according to the invention, it has proved to be extremely advantageous that the coupling element acts directly on the power transmission means in the pulley or the cable drum and thus the material load in the pulley or the cable drum is greatly reduced. By such an arrangement, a lightweight construction of the pulley is possible, whereby the whole starting device is easier. Since such starting devices are often used in devices such as motor chain saws that already have a significant weight anyway, any weight saving is desired.

Advantageous embodiments of the invention are characterized in the subclaims.

According to a preferred embodiment of the starting device according to the invention is the feature of the pulley or the cable drum and the Power transmission means provided in the engaging end of the coupling element in the starting device, that the power transmission means is guided by the pulley or the cable drum and is articulated to the coupling member. In this case, therefore, the coupling element should be designed so that the power transmission means, such as a pull rope, can be attached thereto.

According to a further preferred embodiment of the invention, the starting device is provided such that the coupling member comprises a wire-wound three-dimensional spring whose first, the pulley or drum facing winding has a smaller cross-sectional area, as a subsequent turn.

In the prior art, a proposal has been developed in which the designed as a spiral spring elastic coupling member is rotated in the starting mode by a twist angle of about 270 degrees to about 280 degrees, whereby a good start of the engine is given. Upon reaching this maximum angle of rotation, the coil spring then applies partially due to their associated with the rotation reduction to the shaft. By this application of the coil spring to the shaft, there is a block against further rotation, so that the driver element of the crankshaft ultimately ends up forced to rotate with the cable pulley or cable drum. As a result, different spring characteristics can be set.

In the DE 203 01 182 U1 It has been proposed that the angle of rotation by which the driver member is rotatable under stress of the elastic coupling member with respect to the sheave or rope drum can be limited to a definable maximum angle value, whereby the maximum load of the coupling element can be predetermined. This can be done for example by a stop.

From the DE 203 19 902 U1 It is also known, in the space between the pulley or cable drum, in particular the axis of the pulley or cable drum, and the coupling member or the driver member, in particular the axis of the driver member to provide at least one thin-walled bush or sleeve, by means of which this gap at least partially is fillable, provide.

In all of these known from the prior art embodiments of the coupling element further components or component elements in the starter device are required, which lead to an additional effort.

According to the described preferred embodiment of the invention, in a starter device, the coupling member having a three-dimensional spring wound from wire will now be provided such that its first winding facing the pulley or rope drum has a smaller cross-sectional area than a subsequent winding. This increases the life of the spring. This minimizes the deformations, i. the fracture-endangered area of the spring is relieved.

A cross-sectional area here is to be understood as the area enclosed by a turn.

With an embodiment of the starting device according to the invention, it is now possible for a load of the spring, it comes first from a certain strength on the bearing journal of the starter housing to the plant.

By this configuration, a breakage of the spring, which usually occurs at overload at this point, can be prevented, since the first smaller spring coil comes to rest on the journal of the housing.

Thus, it is possible by such a modified embodiment of the coupling member according to the invention, without further component changes, to prevent overloading of the coupling element.

According to a preferred embodiment of the present invention, the cross-sectional areas of the spring from the second of the sheave or drum facing winding decrease in size to the driver member facing the end substantially.

In such an embodiment of the coupling element whose tapered shape follows the incoming cooling air flow of the ventilation elements of the housing.

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 arranged behind the starter fan and thus a good flow of a pole wheel can be achieved.

Another advantage of using a spring wound from wire, the cross-sectional areas of which is substantially smaller from the second turn to the other end, that also the space requirement in the starter is lower.

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.

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 0.70 and particularly preferably about 0.75.

Preferably, the wire diameter of the spring is in the range of 2.5 to 3 mm and, according to another preferred embodiment, is about 2.8 mm.

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 Darstellung einer Startvorrichtung gemäß des Standes der Technik;
• Fig. 3 eine schematische Darstellung einer Startvorrichtung gemäß einer bevorzugten Ausführungsform; und
• Fig. 4 drei verschiedene Ansichten eines Kopplungselementes gemäß einer bevorzugten Ausführungsform der Erfindung.

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 representation of a starting device according to the prior art;
• Fig. 3 a schematic representation of a starting device according to a preferred embodiment; and
• Fig. 4 three different views of a coupling element according to a preferred embodiment of the invention.

In the representations 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.

Preferred embodiment of the invention

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

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 20/20 ', in which a coil spring 26/26' is arranged and which is in engagement with a Klinkenmitnehmergliedes 25 '.

The outer, that is, the pulley or cable drum 17,17 'facing the end of the coil spring 26,26' is mounted according to the representation of the prior art in a slot 27 ', in an annular shoulder of the pulley or cable drum 17 'is provided. This shoulder encloses the coil spring 26 ', the outer winding rests against the inner wall of the paragraph. The Klinkenmitnehmerglied 25 'facing the end of the coil spring 26' is mounted in the Klinkenmitnehmerglied 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 'according to the embodiment of the prior art is set in rotation by pulling on the starter cable or pull rope, the pulley or cable drum 17' via the coil spring 26 'with the Klinkenmitnehmerglied 25' with. By means of this ratchet driver member 25 'is thus the rotational movement of the pulley or cable drum 17' and thus the torque to the driven motor shaft transferable.

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 and Fig.2 illustrated embodiment according to the prior art, the coil spring 26 in the Fig. 3 according to a preferred embodiment of the present invention shown integrated into the pulley or cable drum 17, that one end of the pull rope is guided for example by a hole in the pulley or cable drum 17 to the coil spring 26 and at this on a hook 12 of the coil spring 26 in the nodal chamber 18 attached. In a very simple embodiment, this could for example be done by putting a knot in the pull rope, the hook 12 for this purpose is advantageously designed as an eyelet.

Further, the coil spring according to the in FIG. 3 and 4 shown embodiment formed such that the first, the pulley or cable drum 17 facing winding 13 has a smaller cross-sectional area, as a subsequent winding. This smaller spring coil 13 bends when, then mainly at this point occurring at break, by first coming to rest on the spring 26 in the journal when loaded.

From the second winding to the spring 26 is formed as a truncated cone, whose 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 ,

reference numeral

100/100 '

starter

10/10 '

casing

11 '

vents

12

hook

14 '

pivot

15/15 '

spring housing

16/16 '

starter spring

17/17 '

Pulley or rope drum

18

node chamber

20 '

Reception room of the pulley or rope drum

25 '

pawl driver

26/26 '

spiral spring

28 '

fixing screw

Claims (8)

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 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,
   characterised in that
   the other end of the coupling element (26) is in engagement with the cable sheave (17) and is in engagement with the pull cable in such a manner that the pull cable is guided through the cable sheave (17) and is linked on the coupling element (26).
2. The starting device according to one of the preceding claims, characterised in that the coupling element (26) has a three-dimensional spring wound from wire, the first winding thereof, which faces the cable sheave (17), has a smaller cross-sectional area than a subsequent winding.
3. The starting device according to one of the preceding claims, characterised in that the cross-sectional areas of the spring (26) diminish from the second winding facing the cable sheave (17) towards the end facing the driver element.
4. The starting device according to one of the preceding claims, characterised in that, starting from the second winding facing the cable sheave (17), 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.
5. The starting device according to one of the preceding claims, characterised in that, starting from the second winding facing the cable sheave or cable drum (17), the wound spring (26) is a tapering spiral spring.
6. The starting device according to one of the preceding claims, characterised in that a ratio of the diameters from the first to the second winding of the wound spring (26) facing the cable sheave (17) is 0.9 or less.
7. The starting device according to one of the preceding claims, characterised in that the ratio of the diameter lies in the range from 0.8 to 0.70 and is preferably approximately 0.75.
8. The starting device according to one of the preceding claims, characterised in that a wire diameter of the spring lies in the range from 2.5 to 3 mm and is preferably approximately 2.8 mm.

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