DE102007035371B4 - Motor operated implement - Google Patents

Abstract

Drive arrangement for a working device, in particular a chain saw, with a fresh air inlet (13) and an intake manifold (2, 3, 4) arranged downstream of the fresh air inlet (13) in the flow direction (S) of the fresh air and discharging into a carburettor (1) Combustion engine, which is arranged downstream of the carburetor (1) in the direction of flow of an air-fuel mixture produced in the carburetor (1), at least one heat-conducting fin (14) connected to the carburetor (1), projecting outside and coming into contact with ambient fresh air. is provided, characterized in that the intake manifold (2, 3, 4) has a carburetor outer wall contacting inner Ansaugkrümmerwand (6) and a carburetor off the at least one cooling fin (14) having the outer intake manifold wall (3, 9).

Description

Technical area

The invention relates to a drive arrangement for a working device, in particular a chainsaw, having a fresh air inlet and an intake manifold arranged in the flow direction of the fresh air to the fresh air inlet, which opens into a carburetor and an internal combustion engine, in the flow direction of an air-fuel mixture produced in the carburetor after the carburetor is arranged.

State of the art

Motors for motor chain saws can according to the prior art have an internal combustion engine and an upstream carburetor. During operation of the internal combustion engine, a thermal equilibrium is formed in the cylinder of the internal combustion engine. The heat generated by the combustion of the fuel-air mixture in the combustion chamber is discharged on the one hand by the hot exhaust gases, on the other hand, the cylinder surrounding the combustion chamber is cooled by the newly flowing cooler air-fuel mixture. This balance keeps the temperature of the cylinder constant. The balance is interrupted immediately after switching off the internal combustion engine. On the one hand there is no removal of heat by outflowing exhaust gases, on the other hand, the cooling effect is canceled by the entering into the combustion chamber fuel-air mixture. The short-term, significantly increased temperature of the cylinder is also delivered via the fuel-air mixture duct to the carburetor. This heats up the carburetor. The heat in the carburetor claims this disadvantageously.

In the US 4,256,093 A is a multi-cylinder internal combustion engine with Wärmeleitflächen on the outer wall of the air and Kaftstoffzufuhrkanäle described. Through them, heat is absorbed from the hot exhaust passage to preheat the flow entering the combustion chamber.

In the DE 201 02 026 U1 an arrangement of a heat-dissipating member is proposed at a location remote from the internal combustion engine, whereby a not inconsiderable amount of heat is dissipated by a heat-conductive contact with the carburetor.

DESCRIPTION OF THE INVENTION: Problem, Solution, Advantages

It is an object of the present invention to provide a drive arrangement for a working device in which the carburetor is exposed to a lower thermal load.

The object is achieved by a drive arrangement with the features of the main claim.

The drive assembly is for implements, especially hand-held implements, such as chainsaws, cutters, hedge trimmers determined. The drive arrangement has a fresh air inlet and an intake manifold arranged downstream of the fresh air inlet in the direction of flow of the fresh air. The intake manifold opens into an air intake of a carburettor. The drive arrangement further comprises an internal combustion engine provided after the carburetor internal combustion engine, preferably a 4-stroke internal combustion engine. However, it is also conceivable to provide 2-stroke internal combustion engines. According to the invention, the drive arrangement has at least one heat conductively connected to the carburetor, outside projecting and with fresh air coming into contact with the cooling fin. In particular, shortly after the switching off of the internal combustion engine, additional heat is emitted from the cylinder of the internal combustion engine comprising the combustion chamber via a fuel-air mixture duct to the carburetor. As a result, the carburetor usually heats up quickly in the short term. The at least one cooling fin releases heat, in particular shortly after switching off the drive arrangement, thus protecting the carburettor.

Preferably, the at least one cooling fin projects from an outer intake manifold wall of the intake manifold disposed between the carburetor and the at least one cooling fin. The intake manifold is preferably made entirely of particularly good heat conductive material.

The intake manifold may be bounded on the carburetor side by an inner intake manifold wall contacting an outer carburetor wall and, on the carburetor side, by an outer intake manifold wall having the at least one cooling fin. The heat removal from the carburetor takes place via the contact surface to the inner intake manifold wall via preferably two short side intake manifold walls and an intake manifold bottom to the outer intake manifold wall. From there, the heat is radiated through the at least one cooling fin. The described arrangement of the at least one cooling rib can be produced in a cost-effective manner by only a minor redesign of already used intake manifolds.

In another aspect of the invention, the intake manifold has access for lubricant into the fresh air stream. The drive assembly according to the invention comprises in the flow direction of a fuel-air mixture behind the carburetor to a sampling piece for a small part of the fuel. The small part of the fuel is in fed to the lubricant circuit and used with the addition of oil as a lubricant. The drive assembly and possibly other components are lubricated by the fuel oil. Further addition of lubricants is not required. The lubricant is returned to the combustion after flowing through the entire lubricant circuit. For this purpose, an access for the lubricant is provided in the intake manifold.

The fresh air flowing in the intake manifold absorbs the lubricant exiting there and supplies it to the carburetor as air - with a low proportion of fuel. In the carburetor further fuel in controllable amount is added to the air and a fuel-air mixture is formed, which is then supplied to the internal combustion engine for combustion.

Along the lubricant circuit, the lubricant heats up. In order to be able to deliver a great deal of heat from the lubricant to the fresh air through the inventive at least one cooling fin, a heat-conducting lubricant channel is provided in the current direction of the lubricant before access, the heat is conductively connected to the at least one cooling fin in combination.

Preferably, the lubricant channel is guided along the outer intake manifold wall. In particular, when the at least one cooling fin protrudes from the outer intake manifold wall, there is a particularly good heat-conducting connection between the lubricant duct and the cooling rib.

Conveniently, the intake manifold is composed of several parts. The intake manifold may include an outer wall member disposed between an intake manifold component and an air filter component with the fresh air intake, and an outer wall of the intake manifold component and the outer wall member and an outer wall of the air cleaner component may form the outer intake manifold wall. The intake manifold component preferably has an air passage having a generally oblong rectangular cross-section transverse to the flow direction which is preferably bounded by the inner, outer and two lateral intake manifold walls sloping from the inner to the outer intake manifold wall. The preferred multi-part design of the intake manifold allows for more comfortable maintenance and accessibility of the carburettor.

Several cooling fins can be arranged particularly advantageously parallel to each other, wherein the one ends of the cooling fins are aligned with each other and connected by a transverse strip and the other ends of the cooling fins are interconnected by a U-shaped arc. The cooling fins thus form a preferably one-piece and therefore cost-mountable component.

Preferably, the intake manifold made of light metal, in particular aluminum. Aluminum is particularly heat-conducting.

The drive arrangement is preferably installed in a working device. In this case, the at least one cooling fin is arranged so that they are easily accessible for fresh air, or for example, openings in the housing of the implement allow the contact of the at least one cooling fin to the fresh air.

Brief description of the drawings

The invention will be described with reference to an embodiment in three figures. In a purely schematic representation:

1 a perspective view of a portion of a drive assembly according to the invention,

2 a rear view of an intake manifold component, and

3 a front view of the intake manifold in 2 ,

Best way to carry out the invention

In 1 is partially obscured a carburetor 1 shown. An intake manifold 2 . 3 . 4 has an intake manifold component 2 and an outer wall member inserted therein 3 and an air filter component hooked therein 4 on. An inner intake manifold component wall 6 the intake manifold component 2 is applied laterally to an outer carburetor wall under extensive contact. The interface between carburetor 1 and inner intake manifold component wall 6 is good heat conductive.

The carburetor 1 has at its the intake manifold component 2 facing carburetor wall an air inlet 7 for through the intake manifold 2 . 3 . 4 supplied air. The carburetor 1 Incoming air is already a mixture of originating from the environment fresh air with a supplied low fuel oil content. In the inner wall 6 the intake manifold component 2 is one with the air intake 7 aligned opening 8th intended. The inner wall 6 and an outer wall 9 the intake manifold component 2 and on them vertical intake manifold side walls 11 form a duct cut, and they are double-walled at the upper open edge. 1 shows the intended in operation orientation of the components to each other and to the ground.

An intake manifold component 2 facing edge of the outer wall element 3 is in the double-walled rim of the intake manifold component 2 plugged in. An intake manifold component 2 opposite end of the outer wall element 3 is with a hooking mechanism 12 fitted. The hooking mechanism 12 allows the hooking of a bottom free edge of the air filter component 4 , The air filter component 4 has a fresh air inlet 13 on. In the air filter component 4 is downstream of the fresh air inlet 13 a (not shown) air filter provided.

The fresh air drawn in from outside flows through the air inlet 13 of the air filter component 4 through the air filter, inside along the outer wall element 3 into the intake manifold component 2 , The intake manifold component 2 is formed in a cross section perpendicular to the current direction S of the fresh air is substantially elongated rectangular. In the intake manifold component 2 the fresh air mixes with lubricant, which by a - in 1 through the holder 3 concealed - access to the intake manifold component 2 is ushered in. The provided with a small amount of lubricant fresh air is then as air to the carburetor 1 fed.

In the carburetor 1 The air flows throttled along a venturi (not shown) along a venturi and controllably absorbs a certain amount of fuel. The resulting fuel-air mixture flows from one - through the carburetor 1 concealed - fuel-air mixture outlet from the carburetor 1 in a fuel-air mixture inlet of the (not shown) internal combustion engine. The internal combustion engine is designed here as a 4-stroke engine.

The intake manifold component 2 indicates on its outer intake manifold component wall 9 arranged parallel to each other cooling fins 14 on. The cooling fins 14 are arranged vertically and aligned substantially parallel to the current direction S. The upper, the air filter component 4 facing ends of the cooling fins 14 are aligned with each other and, they are interconnected by a heat conductive strip, while a heat conductive connecting strips of the lower ends of the cooling fins 14 a U-shaped arch 16 formed.

At the carburetor 1 are three screws 17 intended. On the upper carburetor wall is a connection on the outside 18 intended for the fuel pump. The intake manifold component 2 has at the the air filter component 4 opposite end of a connecting piece 19 for a lubricant hose on.

Between the carburetor 1 and the internal combustion engine is provided for a small amount of fuel (not shown). About 3% of the fuel flowing through the sampling piece is removed. The extracted fuel can be fed to the lubricant circuit and is used exclusively as a lubricant. The drive assembly according to the invention thus does not require a separate lubricant supply. The extracted lubricant through the sampling piece in the form of fuel oil is conveyed into the lubricant circuit and at the end of the circuit via the connecting piece 19 into the intake manifold component 2 passed to be taken from there by passing fresh air and as air with low fuel content in the carburetor 1 to be guided.

2 shows the intake manifold component 2 in a rear view. The rear view is the view from the carburetor 1 out. The intake manifold component 2 has the through the inner intake manifold component wall 6 guided opening 8th on. Furthermore, mounting holes 21 for tightening the intake manifold component 2 on the carburetor 1 intended. The inner intake manifold wall 6 has one in the air duct through an access 22 opening lubricant pipe 23 on. At the access 22 opposite end of the lubricant pipe 23 is the connection piece 19 intended for the lubricant hose.

3 shows the front view of the intake manifold 2 in 2 , The opening 8th in the inner intake manifold wall 6 is from the outer intake manifold wall 9 About half hidden. The inner and outer intake manifold wall 6 . 9 form two interfaces of the air duct of the intake manifold 2 out. The two lateral boundary walls are also from a double-edged side intake manifold wall 11 educated. Outside on the outer intake manifold wall 9 are several heat conductive interconnected cooling fins 14 intended. The cooling fins 14 are in turn heat conducting with the outer intake manifold wall 9 connected.

The cooling fins 14 On the one hand radiate the heat from the carburetor 1 is recorded. On the other hand, the cooling fins radiate 14 passing through the lubricant through the lubricant pipe 23 emitted heat.

During operation, in particular, the cylinder of the internal combustion engine heats up strongly. However, there is a thermal equilibrium in the cylinder during operation. The heat development by combustion of the fuel-air mixture and the heat release by removal of the hot exhaust gas, as well as the additional cooling effect by flowing into the cylinder cold air-fuel mixture are in equilibrium. This balance is canceled immediately after switching off the internal combustion engine. The cylinder heats up in the short term in addition. This short-term additional heating of the cylinder is based on the fact that the removal of heat by escaping exhaust gases is suddenly stopped and that the supply of the cool fuel-air mixture into the cylinder is just as suddenly prevented. The radiating heat from the cylinder passes in particular via a metallic fuel-air mixture channel between the engine and carburetor 1 in the adjacent carburetor 1 and heats it up a lot. The carburetor 1 absorbed heat is through the cooling fins of the invention 14 delivered directly to the fresh air of the environment.

The drive device described is part of a drive of a working device, in particular a hand-held implement such as a chainsaw. The cooling fins 14 are in direct contact with the ambient air surrounding the implement.

The non-illustrated lubricant circuit begins at the (not shown) sampling piece downstream of the carburetor 1 , The fuel passes through a check valve via a lubricant line in the crankcase. From there it is stimulated and promoted by the Kolbenhubunter- and overpressure via a separate line in the cylinder head, where it lubricates butterfly valves and the like. A second check valve ensures a clear flow direction. From the cylinder head, the lubricant enters the control chamber of the camshaft, from where it passes through the lubricant channel 23 in the intake manifold 2 is promoted back. During its passage through the lubricant circuit, the lubricant absorbs heat. At least part of this absorbed heat is in the area of the lubricant channel 23 by the heat conductive connection of the lubricant channel 23 with the cooling fins 14 delivered to the outside of the drive assembly existing fresh air.

LIST OF REFERENCE NUMBERS

1

carburettor

2

Ansaugkrümmerbauteil

3

outer wall element

4

Air filter component

5

6

inner intake manifold component wall

7

air intake

8th

opening

9

outer intake manifold component wall

10

11

lateral intake manifold walls

12

Einhakmechanismus

13

Fresh air inlet

14

cooling fins

15

16

U-shaped bow

17

screws

18

Connection for fuel pump

19

spigot

20

21

fastening opening

22

Access

23

Lubricant tube SSstream direction

S

current direction

Claims (12)

Drive arrangement for a working device, in particular a chain saw, with a fresh air inlet ( 13 ) and one in the flow direction (S) of the fresh air to the fresh air inlet ( 13 ) arranged intake manifold ( 2 . 3 . 4 ) in a carburettor ( 1 ) and an internal combustion engine, in the flow direction of a carburetor ( 1 ) produced air-fuel mixture after the carburetor ( 1 ), wherein at least one heat conducting with the gasifier ( 1 ), externally projecting and with fresh air coming into contact cooling rib ( 14 ), characterized in that the intake manifold ( 2 . 3 . 4 ) an inner intake manifold wall contacting a carburettor outer wall ( 6 ) and a carburetor off the at least one cooling fin ( 14 ) having outer intake manifold wall ( 3 . 9 ) having. Drive arrangement according to claim 1, characterized in that the intake manifold ( 2 . 3 . 4 ) an access ( 22 ) for lubricant in the fresh air stream. Drive arrangement according to claim 2, characterized in that in the flow direction of the lubricant before access ( 22 ) a heat-conducting with the at least one cooling fin ( 14 ) connected lubricant channel ( 23 ) on the intake manifold ( 2 . 3 . 4 ) is provided. Drive arrangement according to claim 3, characterized in that the lubricant channel ( 23 ) along the outer intake manifold wall ( 3 . 9 ) runs. Drive assembly according to claim 1, characterized in that the intake manifold between a Ansaugkrümmerbauteil ( 2 ) and an air filter component ( 4 ) with the fresh air inlet ( 13 ) arranged outer wall element ( 3 ) and an outer wall of the intake manifold ( 2 ) the outer wall element ( 3 ) and an outer wall of the air cleaner component form the outer intake manifold wall. Drive arrangement according to claim 5, characterized in that the inner intake manifold wall ( 6 ) one with an air inlet ( 7 ) of the carburettor ( 1 ) aligned opening ( 8th ) having. Drive arrangement according to claim 5 or 6, characterized in that the intake manifold component ( 2 ) has an air channel with a cross-section transverse to the current direction (S) has a substantially oblong rectangular cross-section, which through the inner ( 6 ), the outer ( 9 ) and two lateral ones of the inner ( 6 ) to the outer intake manifold wall ( 9 ) sloping intake manifold walls ( 11 ) is limited. Drive arrangement according to claim 7, characterized in that a circumferential wall of the air duct is formed double-walled and a bottom edge in operation of the outer wall element ( 3 ) and an operating edge facing away from the ground a Einhakmechanismus for the air filter component ( 4 ) having. Drive device according to claim 2, characterized in that the access ( 22 ) forms an end portion of a lubricant circuit. Drive device according to claim 1, characterized in that the intake manifold consists of light metal. Drive device according to at least one of the preceding claims, characterized in that a plurality of cooling fins ( 14 ) are arranged parallel to each other and the one ends of the cooling fins ( 14 ) are aligned with each other and connected by a transverse strip and the other ends of the cooling fins are interconnected by a U-shaped arc. Working tool, in particular motor chain saw, with a drive arrangement according to at least one of the preceding claims, characterized in that the at least one cooling rib ( 14 ) are in contact with the fresh air of the environment.

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