US20130306007A1

US20130306007A1 - Device for providing clean combustion air for the internal combustion engine of a working tool

Info

Publication number: US20130306007A1
Application number: US13/891,414
Authority: US
Inventors: Joerg ACHENBACH
Original assignee: Makita Corp
Current assignee: Makita Corp
Priority date: 2012-05-15
Filing date: 2013-05-10
Publication date: 2013-11-21
Also published as: DE202012101780U1; CN103422963A; GB201308359D0; GB2503979A

Abstract

In a device for providing clean combustion air for an internal combustion engine of a working tool, provision is made for a cyclone filter into which ambient air contaminated with impurities can be sucked. A partial air flow contaminated with impurities can be extracted by suction from the cyclone filter, a partial air flow substantially freed from impurities is branched off from the cyclone filter and supplied to the internal combustion engine as combustion air. A fan which provides a flow of cooling air against the internal combustion engine, is at least partially accommodated in a housing. Provision is made in the housing for at least one suction bore, which leads into the housing and provision is made in the area of the suction bore for a flow element for creating a low pressure. The partial air flow contaminated with impurities is connected to the suction bore.

Description

The instant invention relates to a device for providing clean combustion air for the internal combustion engine of a working tool, in particular of a handheld working tool, such as a chainsaw, an angle grinder, a working tool for the yard and landscape maintenance and the like, wherein provision is made for a cyclone filter, into which ambient air, which is contaminated with impurities, can be sucked, wherein a partial air flow, which is contaminated with impurities, can be extracted by suction from the cyclone filter, wherein a partial air flow, which is substantially freed from impurities, is furthermore branched off from the cyclone filter and can be supplied to the internal combustion engine as combustion air, and wherein provision is made for a fan, by means of which cooling air can flow against the internal combustion engine and wherein the fan is at least partially accommodated in a housing.

PRIOR ART

A device for providing clean combustion air for the internal combustion engine of a working tool, which is embodied as an angle grinder, for example, is known from DE 10 2004 058 136 A1. The device comprises a cyclone filter, into which ambient air, which is contaminated with impurities, is sucked, wherein a partial air flow, which is contaminated with impurities, is extracted by suction from the cyclone filter, wherein the extraction by suction is created by means of a low pressure, which is created by means of the rotary motion of a fan. For this purpose, the fan encompasses a so-called rear blading, through which, in an outlet port, into which the partial air flow that is contaminated with impurities leads, is sucked. Disadvantageously, an installation space is required for the rear blading of the fan, and the front blading of the fan, which serves to provide a cooling air, by means of which the internal combustion engine, in particular the cylinder of the internal combustion engine is cooled, must be embodied so as to be smaller due to the limited installation space of the fan in a housing, whereby only a smaller quantity of cooling air can be provided to the internal combustion engine.
A further device for providing clean combustion air for the internal combustion engine of a working tool, which is also embodied as an angle grinder, for example, is known from DE 20 2006 002 330 U1. To create a partial air flow, which is contaminated with impurities, for a cyclone filter, a low pressure is also provided by means of a fan, which substantially serves to cool the internal combustion engine and in particular the cylinder of the internal combustion engine. A bore, which is fluidically connected to the partial air flow of the cyclone filter, which is contaminated with impurities, is created in the central axis of rotation of the fan. In the event that the fan is rotated, for example in that the fan is connected to the crankshaft of the internal combustion engine, a low pressure that finally serves to extract the partial air flow, which is contaminated with impurities, from the cyclone filter by means of suction, is created in the hub of the fan. Disadvantageously, the suction effect is limited by means of such an arrangement via the hub of the fan.

DESCRIPTION OF THE INVENTION

Object, Solution, Advantages

It is thus the object of the instant invention to further develop a device for providing clean combustion air for the internal combustion engine of a motorized working tool such that said device is embodied so as to save installation space and so as to be efficient. It is in particular the object of the instant invention not to use any additional elements, by means of which the low pressure is created in the partial air flow, which is contaminated with impurities.
This object is solved based on a device for providing clean combustion air according to the preamble of claim 1, based on a method for providing clean combustion air according to the preamble of claim 9 and based on a working tool comprising a device for providing clean combustion air according to claim 11, in each case with the respective characterizing features. Advantageous further developments of the invention are specified in the dependent claims.
The invention includes the technical teaching that provision is made in the housing for at least one suction bore, which leads into the housing and that provision is made in the area of the suction bore for a flow element for creating a low pressure, wherein the partial air flow, which is contaminated with impurities, is connected to the suction bore.
The invention is based on the idea of forming a Venturi nozzle, by means of which a low pressure can be created in the known manner, by means of a suction bore and a flow element in the housing, in which the fan is accommodated. For this purpose, provision is made according to the invention in the housing for a suction bore, which leads into the area, in which the fan is accommodated in the housing. In the event that the internal combustion engine of the working tool is operated, the fan typically rotates permanently about an axis, which is formed by means of the crankshaft of the internal combustion engine, for example. A low pressure is thus permanently provided in the suction bore, which can be connected to the cyclone filter. The connection between the suction bore of the Venturi nozzle in the housing and the cyclone filter can be established by means of a hose connection or by means of a pipe connection, by means of which the partial air flow, which is contaminated with impurities, is created. The contaminated partial air flow can thus be extracted by suction from the cyclone filter and can be guided into the housing, and the air flow in the housing, which is created by means of the fan, only serves to cool the internal combustion engine, in particular the cylinder of the internal combustion engine. This does not disadvantageously impact the function of the internal combustion engine and the formed Venturi nozzle does not require any additional installation space. An effective separation of impurities from the partial air flow, which is supplied to the internal combustion engine as combustion air, for example after passing through a further filter for fine-dedusting, can be ensured due to the high suction effect in the suction bore by utilizing the Venturi nozzle effect.
For example, the housing can encompass a flow chamber, in which the fan is arranged so as to rotate about an axis, wherein the suction bore leads into the flow chamber, in particular wherein the fan creates an air flow in the mouth area of the suction bore. The flow chamber can encompass a snail shell-like contour, for example, and the suction bore can be embodied so as to be oriented radially towards the axis of the fan, for example. In the alternative, the suction bore in the bottom wall of the housing can extend parallel to the axis of the fan. The fan can be embodied as tangential fan, so that the fan wheel is flown against approximately axially, for example, and the air to be supplied to the internal combustion engine is initially accelerated into a rotary motion about the axis, so that the air flow is created in the mouth area of the suction bore. The air flow can subsequently leave the fan area approximately tangentially, wherein at least one suction bore can preferably be introduced into an area in the housing, in which the air flow is particularly strong, so as to create a correspondingly strong suction effect in the suction bore.
By providing the low pressure for the partial air flow, which is contaminated with impurities, according to the invention by arranging a Venturi nozzle in the housing for accommodating the fan, the construction of a fan is made possible, which is only equipped on one side with fan blades, which serve to create the air flow in the mouth area of the suction bore. By means of the one-sided blading of the fan, the air flow for cooling the internal combustion engine can be embodied in a particularly strong manner, because the fan blades can be embodied so as to be larger than when the fan encompasses a rear blading, which would only serve to create a low pressure.
According to a possible advantageous embodiment of the flow element, it can form a constriction contour in a housing part of the housing, in particular in the housing part, into which the suction bore leads, and/or the constriction contour is embodied so as to be located opposite the mouth of the suction bore in the housing. In both arrangements, a low pressure can be created in the mouth area of the suction bore, because the air flow in the housing is accelerated by means of the flow constriction, whereby the suction effect is created.
The flow element, which is embodied as constriction contour, can encompass the profile of an upper wing side of an airfoil wing, for example, wherein the suction bore leads into the flow chamber, downstream from the highest profile point in the upper wing side. A particularly strong suction effect is utilized through this, because the strongest low pressure prevails downstream from the highest profile point in the upper wing side. The constriction contour in the form of an upper wing side can already be embodied in the injection molding of a plastic housing, for example, so that the housing itself forms the constriction contour. In the alternative, an additional component can be arranged on the inner side of the housing, into which the suction bore has already been introduced for forming the constriction contour.
According to a further possible embodiment, the flow element can be embodied as airfoil wing profile, which is arranged close to the mouth of the suction bore in the housing, here in particular in the flow chamber. The airfoil wing profile can thereby be arranged in the flow chamber, so that the air flow can flow completely around it at least from a bottom wing side and from an upper wing side. The flow element in the form of an airfoil wing profile thus does not only need to be embodied as contour in the housing, but the airfoil wing profile can also be arranged freely in the flow chamber, and a low pressure is created in particular on the upper wing side, so that the airfoil wing profile can be arranged in the air flow, with the upper wing side facing in the direction of the suction bore. It goes without saying that a first flow element, which is embodied as constriction contour in the housing, and a second flow element, which is embodied so as to be arranged freely in the flow chamber as airfoil wing profile, can be combined with one another.
The instant invention is further directed to a method for providing clean combustion air for an internal combustion engine of a working tool, in particular of a handheld working tool, such as a chainsaw, an angle grinder, a working tool for the yard and landscape maintenance and the like, wherein provision is made for a cyclone filter, into which ambient air, which is contaminated with impurities, is sucked, wherein a partial air flow, which is contaminated with impurities, is extracted by suction from the cyclone filter, and wherein a partial air flow, which is substantially freed from impurities, is furthermore branched off from the cyclone filter and is supplied to the internal combustion engine as combustion air, and wherein provision is made for a fan, by means of which cooling air flows against the internal combustion engine. The fan is at least partially accommodated in a housing, wherein at least one suction bore is introduced into the housing and wherein a low pressure is created in the area of the suction bore in connection with at least one flow element, wherein the partial air flow, which is contaminated with impurities, is extracted through the suction bore by suction by means of the low pressure. The features and advantages of the above-described device can also be considered for the method according to the invention.
The invention is further directed to a working tool comprising a device according to the above-described type, in particular for operating a method for providing clean combustion air for an internal combustion engine of the working device according to the above description.

BRIEF DESCRIPTION OF THE DRAWINGS

Further measures, which improve the invention, will be illustrated in more detail below by means of the figures together with the description of preferred exemplary embodiments of the invention.

FIG. 1 shows a perspective view of a working tool comprising a device for providing clean combustion air,

FIG. 2 shows a top view onto a first exemplary embodiment of a device for providing clean combustion air,

FIG. 3 shows a side view of the exemplary embodiment of the device according to FIG. 2 and

FIG. 4 shows a further exemplary embodiment of a device in a top view.

PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 shows an exemplary embodiment of a working tool 100 comprising an internal combustion 11, which is not shown explicitly and which serves to drive a tool 25. The internal combustion engine 11 is supplied with an ambient air 13, which can pass through ventilating slits 26, which are introduced into a housing 17 of the working tool 100. The housing 17 serves primarily to accommodate a fan 16 and for correspondingly guiding an air flow 23 to the internal combustion engine 11, as is illustrated in more detail in the following figures.
In a top view, FIG. 2 shows a part of the working tool 100 according to FIG. 1 comprising a device 1 for providing clean combustion air to the internal combustion engine 11. The housing 17 is illustrated without the housing cover, which is shown with ventilating slits 26 in FIG. 1, and the view shows a further housing part 17 a. A fan 16, which encompasses a plurality of fan blades 24, which are arranged on the front side of the fan wheel, is accommodated in this housing part 17 a so as to rotate about an axis 22. The axis 22 can be formed by an end of the crankshaft of the internal combustion engine 11, for example. The housing part 17 a encompasses an accommodating depression for accommodating the fan 16, and the accommodating depression increases in a radially expanding manner in the direction of the cylinder of the internal combustion engine 11, so that an approximately logarithmic spiral is created, and a flow chamber 21 is formed by means of it. A flow, which substantially rotates about the axis 22 and which is created by means of the guide blades 24 of the rotating fan 16, is created in this flow chamber 21.
According to the invention, a flow element 19 in the form of a constriction contour 19 is embodied in the bottom area of the flow chamber 21, and two suction bores 18 lead into the constriction contour 19. The air flow 23 accelerates above the constriction contour 19, so that a low pressure is created in the air flow 23 according to Bernoulli and a suction is consequently created in the suction bores 18. A detailed illustration of the device 1 for providing clean combustion air 10 for the internal combustion engine 11 in particular in operative connection with the cyclone filter 12 is shown in FIG. 3 in more detail.
FIG. 3 shows a side view of the housing 17, in which the non-illustrated fan 16 is accommodated. The cross sectional view of the housing part 17 a of the housing 17 illustrates the constriction contour 19, through which the suction bore 18 extends and which leads into the flow chamber 21, viewed in flow direction, downstream from the highest profile point 27. The illustration of the air flow 23 shows an acceleration area of the flow above the constriction contour 19, so that a low pressure is created in the mouth area of the suction bore 18.
A cyclone filter 12, into which ambient air 13 is sucked, which is contaminated with impurities, is furthermore shown. A partial air flow 14 is fluidically connected to the suction bore 18, and air, which is contaminated with impurities, can be extracted by suction from the cyclone filter 12 via the partial air flow 14 by means of the low pressure, which is created in the mouth area of the suction bore 18. The embodiment of a Venturi nozzle is thereby created by means of the arrangement of the suction bore 18 in combination with the constriction contour 19, and contaminated air is extracted by suction from the cyclone filter 12 via the partial air flow 14 by means of the Venturi effect.
A further partial air flow 15 leaves the cyclone filter 12 in a state, which is substantially freed from impurities, and the partial air flow 15, which is pre-cleaned by means of the cyclone filter 12, is fine-dedusted by means of a further filter 28, which is embodied as paper filter or fabric filter, for example, and the combustion air 10, which is provided with this, can be supplied to the internal combustion engine 11.
FIG. 4 shows a further exemplary embodiment of a device 1 for providing clean combustion air 10 for the internal combustion engine 11 of a work tool 100 according to FIG. 1. The illustration shows the housing part 17 a of the housing 17, as it is part of the working tool 100 according to FIG. 1. The fan 16 is accommodated in the housing part 17 a so as to rotate about the axis 22, and the fan 16 encompasses fan blades 24 for creating an air flow 23 in the flow chamber 21, which is formed in the housing part 17 a. A suction bore 18, which leads into the flow chamber 21 and thus into the air flow 23, is introduced into the wall of the housing part 17A. As shown in an implied manner, the suction bore 18 is in turn connected to the partial air flow 14 of the cyclone filter 12, through which ambient air 13 is sucked in. The partial air flow 14 is thereby contaminated with impurities and the further provided partial air flow 15 is pre-cleaned and can be supplied to the internal combustion engine 11 of the working tool 100 as combustion air 10 after passing through the filter 28.
The flow element 20 is embodied as airfoil wing profile 20 and is inserted in the flow chamber 21 at a distance upstream of the mouth area of the suction bore 18. In the event that the air flow 23 flows completely around the airfoil wing profile 20, an acceleration of the air flow 23 is created on the upper side of the airfoil wing profile 20, which faces in the direction of the suction bore 18, whereby a low pressure is in turn created again in the mouth area of the suction bore 18. Through this, contaminated air can be extracted by suction from the cyclone filter 12 via the partial air flow 14 in the manner, which has already been described, wherein the impurities enter into the air flow 23, which substantially serves only to cool the internal combustion engine 11.
The embodiment of the invention is not limited to the exemplary embodiments, which have only been shown in an exemplary manner above. Instead, a number of alternatives is possible, which utilizes the illustrated solution even in the case of embodiments, which are of a generally different type. All of the features and/or advantages, which follow from the claims, the description or the drawings, including structural details or spatial arrangements, can be significant for the invention, both alone and in a variety of combinations. In particular, the flow element, embodied in an exemplary manner as constriction contour 19 or as airfoil wing profile 20, can be embodied in any other way so as to create a low pressure in the mouth area of the suction bore 18. In particular, provision can also be made in a flow path of the air flow 23 from the fan 16 to the internal combustion engine 11 for a section, which is geometrically embodied in another way such that the Venturi effect can be utilized, so as to create a low pressure on the side of the partial air flow 14 of the cyclone filter 12. The invention is thus not limited to the arrangement of a corresponding flow geometry in the housing part 17A, and it is possible, for example, to also provide a geometric embodiment for utilizing a Venturi effect in a bypass. For example, the cyclone filter 21 can geometrically adjoin the flow chamber 21 with only one intermediate wall such that a connection as hose line or pipeline for the partial air flow 14 is no longer necessary, and a connection between the cyclone filter 12 and the flow chamber 21 can be limited to the suction bore 18. A combination of the flow elements 19 and 20 is furthermore possible, so that an airfoil wing profile 20 can be provided so as to be spaced apart from a constriction contour 19, wherein both flow elements 19 and 20 are arranged in the air flow 23.

LIST OF REFERENCE NUMERALS

100 working tool
1 device
10 combustion air
11 internal combustion engine
12 cyclone filter
13 ambient air
14 partial flow contaminated
15 partial flow clean
16 fan
17 housing
17 a housing part
18 suction bore
19 flow element, constriction contour
20 flow element, airfoil wing profile
21 flow chamber
22 axis
23 air flow
24 fan blade
25 tool
26 ventilating slits
27 highest profile point
28 filter

Claims

1. A device for providing clean combustion air for the internal combustion engine of a working tool, in particular of a handheld working tool, such as a chainsaw, an angle grinder, a working tool for the yard and landscape maintenance and the like, wherein

provision is made for a cyclone filter, into which ambient air, which is contaminated with impurities, can be sucked,

wherein a partial air flow, which is contaminated with impurities, can be extracted by suction from the cyclone filter,

wherein a partial air flow, which is substantially freed from impurities, is furthermore branched off from the cyclone filter and can be supplied to the internal combustion engine as combustion air,

and wherein provision is made for a fan, by means of which cooling air can flow against the internal combustion engine and

wherein the fan is at least partially accommodated in a housing, characterized in that

provision is made in the housing for at least one suction bore, which leads into the housing and that

provision is made in the area of the suction bore for a flow element for creating a low pressure, wherein

the partial air flow, which is contaminated with impurities, is connected to the suction bore.

2. The device according to claim 1, characterized in that the housing encompasses a flow chamber, in which the fan is arranged so as to rotate about an axis, wherein the suction bore leads into the flow chamber, in particular wherein the fan creates an air flow in the mouth area of the suction bore.

3. The device according to claim 1, characterized in that the air flow serves to flow against the internal combustion engine and in particular the cylinder of the internal combustion engine.

4. The device according to claim 1, characterized in that the fan is equipped on one side with fan blades, which serve to create the air flow in the mouth area of the suction bore.

5. The device according to claim 1, characterized in that the flow element is embodied as constriction contour in a housing part of the housing, in particular into which the suction bore leads and/or the constriction contour is embodied so as to be located opposite the mouth of the suction bore in the housing.

6. The device according to claim 5, characterized in that the flow element, which is embodied as constriction contour, encompasses a profile of an upper wing side of an airfoil wing, wherein the suction bore leads into the flow chamber, preferably downstream from the highest profile point in the upper wing side.

7. The device according to claim 1, characterized in that the flow element is embodied as airfoil wing profile, which is arranged close to the mouth of the suction bore in the housing, in particular in the flow chamber.

8. The device according to claim 7, characterized in that the airfoil wing profile is arranged so that the air flow can flow completely around it at least from a bottom wing side and from an upper wing side, in particular wherein the airfoil wing profile is arranged in the air flow, with the upper wing side facing in the direction of the suction bore.

9. A method for providing clean combustion air for an internal combustion engine of a working tool, in particular of a handheld working tool, such as a chainsaw, an angle grinder, a working tool for the yard and landscape maintenance and the like, wherein

provision is made for a cyclone filter, into which ambient air, which is contaminated with impurities, is sucked,

wherein a partial air flow, which is contaminated with impurities, is extracted by suction from the cyclone filter,

wherein a partial air flow, which is substantially freed from impurities, is furthermore branched off from the cyclone filter and is supplied to the internal combustion engine as combustion air,

and wherein provision is made for a fan, by means of which cooling air flows against the internal combustion engine and

at least one suction bore is introduced into the housing and

wherein a low pressure is created in the area of the suction bore in connection with at least one flow element, wherein

the partial air flow, which is contaminated with impurities, is extracted by suction by means of the low pressure through the suction bore.

10. The method according to claim 9 for providing clean combustion air for an internal combustion engine of a working tool comprising a device for providing clean combustion air for the internal combustion engine of a working tool, in particular of a handheld working tool, such as a chainsaw, an angle grinder, a working tool for the yard and landscape maintenance and the like, wherein

11. A working tool comprising a device according to claim 1, in particular for operating a method for providing clean combustion air for an internal combustion engine of the working tool, in particular of a handheld working tool, such as a chainsaw, an angle grinder, a working tool for the yard and landscape maintenance and the like, wherein

at least one suction bore is introduced into the housing and