WO2017121666A1

WO2017121666A1 - Control device for a diaphragm carburettor

Info

Publication number: WO2017121666A1
Application number: PCT/EP2017/050113
Authority: WO
Inventors: Maria del Mar DIEZ DIAZ; André FEDIER; Norbert Haberland
Original assignee: Dätwyler Schweiz Ag
Priority date: 2016-01-11
Filing date: 2017-01-04
Publication date: 2017-07-20
Also published as: CH712027B1; CH712027A1

Abstract

The invention relates to a control device for a diaphragm carburettor, said control device comprising a control diaphragm and a control lever, wherein the control diaphragm has a central scanning region, a functional region concentrically surrounding and adjacent to the scanning region, and a peripheral securing edge for securing the control diaphragm in the diaphragm carburettor, and wherein the control lever is mounted with a hinge in the diaphragm carburettor in the assembled position, with a first end operatively connected to a control valve of the diaphragm carburettor and with a second end contacting the central scanning region of the control membrane, such that same can scan an axial deflection of the scanning region depending on a operation-dependent pressure change. According to the invention, on the second end, the control lever has a circular scanning plate that is flat on the diaphragm side, wherein the diameter of the scanning plate is greater than 50 per cent, preferably greater than 85 per cent, particularly preferably greater than 90 per cent of the diameter of the scanning region of the control diaphragm.

Description

Control device for a membrane veraaser

Technical area

The invention relates to a control device for a diaphragm carburetor for controlling a fuel supply of an internal combustion engine.

Technical background

Diaphragm carburetors are mainly used in handheld devices, such. As chainsaws, or used in model airplanes, each of which must operate independently of position. Known control membranes are made of fabric-reinforced rubber and have a riveted circular reinforcing plate in the middle (eg EP0608490, DE202005020877, US2013234345). An example of such a control membrane is shown in Figures 1 (a) and 1 (b). The control membrane 1 is held in the carburetor housing with a peripheral fastening edge 11 and closes off a control chamber in a sealing manner. In the control chamber, a spring-loaded control lever 2 is arranged, which presses in the central region of the stiffening plate 12 at its opposite side against the rivets 13 of the control membrane 1, and thus a membrane stroke, respectively. an axial deflection of a central scanning region 14 of the control membrane 1 scans. In this case, the control lever 2 opens a arranged on the other side of the control valve 3. The control chamber is connected to a carburetor chamber of the diaphragm carburetor. The control chamber side facing away from the control diaphragm is exposed to the ambient pressure. During operation of the carburetor causes a carburetor in the room respectively. In the control chamber resulting negative pressure in the range of a few millibars a diaphragm stroke in tenths of a millimeter to millimeter range of the central scanning region 14, which is scanned by the control lever 2 to regulate the fuel supply. To increase the maximum diaphragm stroke, the control diaphragm 1 has a peripheral bead 15 concentrically surrounding the reinforcing plate 12. The riveted stiffening plate 12, which has a radius of over 50% of the radius to the circumferential fastening edge 11, stiffens a large inner region of the control diaphragm 1. The stiffening plate causes a uniform diaphragm stroke over the area covered by the stiffening plate. That is, this relatively large central scanning region 14 oscillates in the ideal case evenly in the axial direction. However, under real conditions, the stiffening plate 12 tends to "wobble", that is, the stiffening plate 12 can be easily tilted out of the diaphragm plane, especially with rapid changes in the position of the carburetor, which can lead to irregularities in the carburettor control during operation. These position-dependent irregularities are also increased by the relatively large mass of the stiffening plate 12.

To remedy this and other problems, a control membrane has been described in the not yet public Swiss patent application CH00516 / 15 the same applicant, which is made of a non-elastomeric, uniformly thick plastic film. In the control membrane a plurality of functional area forming concentric beads are formed, which defines a central scanning of a few millimeters in diameter. Depending on the configuration of the functional region, the axial deflection of the central scanning region is dependent on the operational pressure change in the control chamber in accordance with a predefined path-pressure characteristic. Such a control membrane has improved response and control behavior over the known control membranes with stiffening plate.

Control levers, which form a control device together with the control diaphragm, are known for example from EP1391605, EP1098084, EP1098084, WO2014018723, US4563311, US4978478, US20070182032, US3268216 and US3174731.

EP1391605 shows a control lever with a convexly curved to the control diaphragm scanning arm. The rule membrane is flat and formed without beads and made of a composite material of fabric and rubber. The contact area of the control lever is made of a non-abrasive material.

EP1098084 shows a control lever with a planar end-to-end sensing arm which contacts a rivet of the control diaphragm. WO2014018723 likewise shows a control lever with a scanning arm rounded in a convex manner to the control diaphragm, which contacts a central scanning region of the control diaphragm.

US4563311 describes a temperature-sensitive control lever which contacts a rivet of the control membrane.

US4978478 shows a control lever with a bolt-shaped contact part, which presses against the control diaphragm. The control membrane has a central stiffening part.

US20070182032 and US3268216 each describe a control lever which is movably connected to the control diaphragm.

US3174731 describes a spring-loaded lever with an opening for receiving a centering pin. On a membrane-remote side of the lever, a spring is provided, in which extends the centering pin. On the membrane-facing side of the lever, the centering pin holds a metal transfer plate on the lever by inserting it into a hole in a central recess of the plate. The plate lies loosely on the flat control membrane.

Presentation of the invention

An object of the invention is to provide a control device for membrane carburetor, in which the response and control behavior of a control membrane resp. the control device is further improved. In particular, the already very good response and control behavior of a control device with a control membrane according to CH00516 / 15 is to be improved.

This object is achieved by a control device for membrane carburetor with the features of claim 1. The control device comprises a Regulating diaphragm and a control lever. The control diaphragm has a central scanning region, a functional region which concentrically revolves the scanning region and delimits the scanning region, and a peripheral attachment border for fastening the control diaphragm in the diaphragm carburetor. In the installed state of the control lever is articulated in the diaphragm carburetor, operatively connected to a first end with a control valve of the diaphragm carburetor and contacted with a second end (Abtastarm) the central scanning of the control membrane, so that it axial deflection of the scanning depending on an operational pressure change in Sampling diaphragm carburetor and can transfer to the control valve. The control lever has at the second end a circular, diaphragm side flat scanning plate, wherein the diameter of the Abtasttellers greater than 50 percent, preferably greater than 85 percent, more preferably greater than 90 percent, of the diameter of the sensing region of the control membrane.

The scanning range corresponds to the central area of the control diaphragm, which is directly delimited by the functional area (ie the inner diameter of the functional area corresponds to the diameter of the scanning area) and experiences the greatest deflection in the operating state. In the conventional rule membranes with riveted stiffening plate, this corresponds essentially to the entire area stiffened by the plate. The functional area defines the area of the control membrane, which mainly defines the flexibility and extensibility of the control membrane. This area is defined in most known membranes by the at least one circumferential bead.

The size of the Abtasttellers is to the diameter of the scanning, which preferably less than 20%, preferably less than 15%, of the inner diameter of the Befestigungsumrandung resp. has outer diameter of the functional area adapted. This allows a better power transmission of the diaphragm stroke on the control lever by a possible, if only very slight depression of the control lever is avoided in the control diaphragm. Such a control device is particularly suitable for integrally formed control diaphragm. The control device is particularly suitable for very thin control diaphragms (eg 5 to 50 microns) without distribution valve.

Preferred embodiments of the invention are indicated in the dependent claims.

In some embodiments, the diameter of the scan plate may be 1 to 4 percent less than the diameter of the scan area, such that the scan plate will deflect even with slight displacements, e.g. B. in the operating state, the functional area of the control membrane does not overlap resp. touched.

In some embodiments, the scanning plate may be integrally formed with the second end of the control lever, e.g. as a one-piece molded plastic or metal part.

In some embodiments, the scanning plate may be formed as a separate part releasably or fixed, e.g. B. by gluing or welding, is connected to the second end of the control lever. A releasable connection may, for example, comprise a pin on the scanning plate, which engages in a hole or a Einbuchten on the second end / Abtastarm the control lever.

In some embodiments, the scanning plate may be formed as a circular broadening of the second end of the control lever. Alternatively, the scanning plate can be placed on the side facing the control membrane on the second end of the control lever.

The entire control lever incl. Scanning plate can be made of the same material. The scanning plate can also be made of a different material than the rest of the control lever material. The material chosen may be a temperarture- and fuel-resistant, non-elastomeric plastic, or a metal. Control lever and / or scanning can be made of the same plastic as the control membrane, z. The plastic may be selected from the group of polybenzimidazole (PBI), polyimides (PI), thermoplastic polyimides (TPI), polyamide-imide (PAI), polyethersulfone (PES), polyphenylsulfone (PPSU), Polyetherimide (PEI), polysulfone (PSU), polyetherketone (PEK), polyaryletheretone (PAEK), polyphenylene sulfide (PPS), perfluoroalkoxy polymer (PFA), ethylene-tetrafluoroethylene (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PCTFE) PVDF), polybutylene terephthalate (PBT), polyetheretherketone (PEEK) and combinations thereof, with a temperature resistance of at least 150 ° C.

In some embodiments, the scan plate may be made of a low friction, non-abrasive material to minimize friction with the scan area.

In all embodiments, the scanning plate may have a diameter of 3 to 6 millimeters.

In connection with the above control device, the following features may be implemented by themselves or in any combination with the aforementioned features:

- The control membrane can be made of a temperartur- and fuel-resistant, non-elastomeric and uniformly thick plastic film.

The functional area of the control diaphragm can have a multiplicity of concentric beads, so that the axial deflection of the scanning range runs as a function of the operational pressure change in the control chamber in accordance with a predefined path-pressure characteristic.

- In the functional area four to ten concentric beads may be formed, which may be formed as concentric circles or concentric Mehrecke.

The concentric beads may be undulating in the radial direction (i.e., a radial section shows a wave-like course).

The corrugations formed in the radial direction may have an amplitude of 0.2 to 1.0 millimeters (from wave crest to wave trough) and / or a wavelength of 1.0 to 2.5 millimeters. The wavelength (w) may increase towards the central scanning area and / or the amplitude may decrease towards the central scanning area. The radius of the scanning area may be less than 20%, preferably less than 15%, of the inner radius of the mounting border and / or the outer radius of the functional area.

The radius of the scanning area resp. the inner radius of the functional area may be 1 to 7 millimeters, preferably 2 to 5 millimeters, and the outer radius of the functional area may be 10 to 25 millimeters.

- In the functional area a plurality of radial stiffening ribs may be formed, which preferably extend only over the innermost concentric beads.

The plastic film may have a thickness of 5 to 200 microns, preferably 10 to 100 microns, more preferably 20 to 50 microns, which is at least approximately the same over the entire control membrane surface or over the functional area and the Befestigungsumrandung.

The control membrane may be made of a plastic selected from the group of polybenzimidazole (PBI), polyimides (PI), thermoplastic polyimides (TPI), polyamide-imide (PAI), polyethersulfone (PES), polyphenylsulfone (PPSU), polyetherimide (PEI), Polysulfone (PSU), polyetherketone (PEK), polyaryletheretone (PAEK), polyphenylene sulfide (PPS), perfluoroalkoxy polymer (PFA), ethylene-tetrafluoroethylene (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polybutylene terephthalate ( PBT), polyetheretherketone (PEEK) and combinations thereof, having a temperature resistance of at least 150 ° C.

- The thickness of the control diaphragm can vary in the radial direction. For example, the scanning range relative to the thickness of the control membrane in

Functional range 2 to 12 times thicker.

Furthermore, the invention relates to a membrane carburetor with a control device according to the invention and the use of the control device according to the invention in a membrane carburetor. Brief explanation of the figures

The invention will be explained in more detail below with reference to embodiments in connection with the (s) drawing (s). Show it :

1 shows a known control device under (a) in a side view and under (b) in a perspective view;

Fig. 2 shows a first embodiment of an inventive

Control device, under (a) in a side view and under (b) in a perspective view;

Fig. 3 of the control lever of FIG. 2, under (a) in a perspective view

View and under (b) in a plan view;

4 shows a second embodiment of an inventive

Control device, under (a) in a side view and under (b) in a perspective view; and

Fig. 5 of the control lever of FIG. 4, under (a) in a perspective view

View, under (b) in a side view and under (c) in a plan view.

Ways to carry out the invention

In FIGS. 1 (a) and 1 (b) a control device known from the prior art is shown. Fig. Fig. 1 (a) shows the control device in a side view. Fig. 1 (b) shows the control device in a perspective view. The control device comprises a control diaphragm 1 and a control lever 2. In both figures, the control diaphragm 1 is shown cut in half.

The control membrane 1 of a rubber-coated fabric has in the center a plate-shaped riveted stiffening plate 12, which forms a central scanning region 14 of the control membrane 1. Immediately following the scanning region 14, the control membrane 1 further comprises a functional region 16 formed from a peripheral peripheral bead 15, which is delimited by a fastening border 11. The control membrane 1 is with the Befestigungsumrandung 11 held in fastening means of a diaphragm carburetor and closes a control chamber sealing (not shown). In the control chamber, the control lever 2 is arranged, which can scan the diaphragm stroke of the control diaphragm 1 and thus controls the fuel supply of the diaphragm carburetor.

The control lever 2 is rotatably mounted in the diaphragm carburetor in the middle on a tilting bearing 5 (here in the form of a pin) and comprises a first end 22, via which it is operatively connected to the control valve 3. Between a second end 22 and the tilting bearing 5, the control lever 2 is loaded with a spring 5, which presses the second end against the control diaphragm and the control valve 3 in a closed position. Pressure-induced deflections of the scanning region 14 of the control diaphragm 1 in the direction of the control chamber cause an opening of the control valve third

The functional region 16 and the scanning region 14 of control membranes 1 is usually circular and, in the installed state, covers a circular control chamber of the membrane carburetor. The outer mounting border, on the other hand, may also deviate from a circular shape, e.g. be designed rectangular.

In Figs. 2 (a) and 2 (b), a first embodiment of a controller is shown. Fig. Fig. 2 (a) shows the control device in a side view. Fig. 2 (b) shows the control device in a perspective view. FIG. 3 shows the control lever from FIG. 2 in a perspective view (FIG. 3 (a)) and in a plan view (FIG. 3 (b)).

The in Fig. 2 consists of a scanning region 14, a functional region 16 and a fastening border 11. Scanning region 14 and functional region 16 define the active exposed region of the control membrane 1, which is deflected due to pressure changes in the control chamber. About the Befestigungsumrandung 11, the control diaphragm 1 is held sealingly in fastening means of the carburetor. A control lever 2 arranged in the control chamber senses the deflection of the Scanning region 14 of the control diaphragm 1 and thus regulates the fuel supply in the carburetor.

The scanning region 14 is essentially planar and merges at the outer edge into the wavy-shaped functional region 16. In the embodiment shown, the scanning region 14 has a radius of less than 20% of the radius of the active region of the control diaphragm 1. The remaining part of the active area is formed by the functional area 16. The scanning region 14 is bounded by the directly adjacent functional region 16, which in the embodiment shown has a multiplicity of concentric beads 15.

The control lever 2 of this embodiment, unlike the above-described control lever 2, has at its second end 21 (i.e., the scanning arm) a circular, plane-side scanning plate 23 on the diaphragm side. That the Abtastteller 23 has no indentations or the like, so that it resp. the central region of the control membrane. more than 85 percent, preferably more than 90 percent of the scanning area contacted over the entire surface. Ideally, the diameter of the scanning plate does not correspond exactly to the diameter of the scanning area, but is 1 to 4 percent lower, so that the scanning plate even with any tolerances of the individual parts, inaccuracies when clamping the control diaphragm or during operation of the carburetor in the deflection of the diaphragm does not affect the functional area.

In the case of the one-piece control diaphragm shown, the scanning region may have a diameter of approximately 5 millimeters. The scanning plate then has a diameter of about 4.8 to 4.9.

Preferably, the control membrane is in the installed state with the bulges of the beads of the control lever oriented away (in the figure above), so that in any slight shifts of the scanning over the scanning the wave crests / troughs of the beads are not touched by the scanning.

A second embodiment of a control device is shown in FIGS. 4 (a) and 4 (b). Fig. 4 (a) shows the controller in one Side view. Fig. 4 (b) shows the control device in a perspective view. FIG. 5 shows the control lever of FIG. 4 in a perspective view (FIG. 5 (a)), in a side view (FIG. 5 (b)) and in a plan view (FIG. 5 (c)).

In contrast to the embodiment of FIGS. 2 and 3, the scanning plate 23 is placed on the scanning arm 21. The scanning plate 23 can be detachably or firmly connected to the scanning 21. In the illustrated embodiment, the scanning plate 23 is slightly spaced from the scanning arm 23 and fixedly or releasably connected by means of a connector. The scanning plate 23 can also be arranged directly on the scanning without connecting piece. In a detachable variant of the Abtasttellers 23, the compound can also be designed articulated, so that the scanning plate 23 can be adapted to slight caused by the diaphragm stroke angle changes the Abtastarms 21 and always rests flat on the scanning area 14.

name list

1 control membrane

11 attachment edge / attachment border

12 stiffening plate

13 rivets

14 scanning range

15 concentric bead

16 functional area

2 control levers

21 second end / scanning arm

22 first end

23 scanning plates

24 connector

3 control valve

4 spring

5 tilting bearings

Claims

claims

Control device for a diaphragm carburetor, the control device comprising a control diaphragm (1) and a control lever (2); wherein the control membrane (1) has a central scanning area (14), a scanning area (14) concentrically encircling and the scanning area (14) limiting functional area (16), and a peripheral Befestigungsumrandung (11) for attachment of the control membrane (1) in the membrane carburetor ; and wherein in the installed state, the control lever (2) is articulated in the diaphragm carburetor, with a first end (22) with a control valve (3) of the Membranvergasers operatively connected and with a second end (21) the central scanning region (14) of the control membrane (1 ), so that it can sense an axial deflection of the scanning region (14) in response to an operational pressure change in the diaphragm carburetor; characterized in that the control lever (2) at the second end (21) has a circular, diaphragm side flat scanning plate (23), wherein the diameter of the Abtasttellers (23) greater than 50 percent, preferably greater than 85 percent, more preferably greater than 90 Percent, of the diameter of the scanning region (14) of the control diaphragm (1).

Control device according to claim 1, characterized in that the diameter of the scanning plate (23) is 1 to 4 percent smaller than the diameter of the scanning region (14).

Control device according to one of the preceding claims, characterized in that the control diaphragm (1) is integrally formed.

Control device according to one of the preceding claims, characterized in that the Abtastteller (23) at the second end (21) of the control lever (2) is integrally formed therewith.

Control device according to one of claims 1 to 3, characterized in that the Abtastteller (23) is formed as a separate part which is detachably or fixedly connected to the second end (21) of the control lever (2).

Control device according to one of the preceding claims, characterized in that the Abtastteller (23) is designed as a widening of the second end of the control lever (2).

Control device according to one of the preceding claims, characterized in that the scanning plate (23) on the said control membrane (1) facing side is placed on the second end of the control lever (2).

Control device according to one of the preceding claims, characterized in that the control lever (2) is made of a temperartur- and fuel-resistant, non-elastomeric plastic or a metal.

Control device according to one of the preceding claims, characterized in that the Abtastteller (23) is made of a relation to the other control lever (2) different material.

10. Control device according to one of the preceding claims, characterized in that the Abtastteller (23) is made of a low-friction, non-abrasive material to minimize friction with respect to the Abtastbereich (14).

11. Control device according to one of the preceding claims, characterized in that the Abtastteller (23) has a diameter of 2 to 14 millimeters, preferably 3 to 6 millimeters.

12. membrane carburetor with a control device according to one of the preceding claims.

13. Use of a control device according to one of claims 1 to 11 as a control device in a diaphragm carburetor.