NO176161B

NO176161B - Knife attachment for electric lawnmower

Info

Publication number: NO176161B
Application number: NO920557A
Authority: NO
Inventors: Eberhard Graf
Original assignee: Wolf Geraete Gmbh Vertrieb
Priority date: 1991-02-22
Filing date: 1992-02-13
Publication date: 1994-11-07
Also published as: EP0499879A1; DE4105557C2; DE59202478D1; ATE123620T1; NO176161C; NO920557L; DE4105557A1; EP0499879B1; NO920557D0

Abstract

What is proposed is a device for fastening rotating fly cutters 18 to the motor shaft 2 of electric lawnmowers, in which a cutter coupling 4 is connected or connectable to the motor shaft 2 by means of a central clamping screw 10. A user-friendly change of the fly cutter 18 in accordance with electrical safety regulations becomes possible in that the clamping screw 10 is received especially with its head within a cavity 14 open at one end and located in a coupling body 4 consisting of insulating material, for example plastic, in that a minimum distance 16 of 8 mm is present between this clamping screw 10, especially the end face of its head, and the free end face 15 of the coupling body or of the cavity orifice, and in that the fly cutter 18 is to be anchored releasably so as to bear against the end face 15 of the coupling body 4 by means of at least one additional screw connection 21 which has a lateral offset position relative to the clamping screw 10 and which is shielded from this by the material of the coupling body. <IMAGE>

Description

Oppfinnelsen gjelder en anordning som angitt i innledningen til patentkrav 1, for å feste roterende vingekniver på motorakselen til elektrisk drevne plenklippere. The invention relates to a device as stated in the introduction to patent claim 1, for attaching rotating blade knives to the motor shaft of electrically driven lawnmowers.

Ved de knivfester av dette slaget for elektrisk drevne plenklippere, som er vanlig i dag, er det i samsvar med VDE- bestemmelse 0701, del 1 og del 2, på basis av DIN 57 701, del 1 og 2, bare tillatt med knivskifte, når det etter avslutningen av skifteoperasjonen henholdsvis etter gjeninnbygging, blir foretatt en høyspenningstest mellom elektromotoren og vingekniven. In accordance with VDE regulation 0701, part 1 and part 2, on the basis of DIN 57 701, part 1 and 2, only blade changes are permitted in the case of blade attachments of this type for electrically powered lawnmowers, which are common today. when, after the end of the replacement operation or after re-installation, a high-voltage test is carried out between the electric motor and the blade.

Et knivfeste for plenklippere, som er slik utformet med hensyn til elektrisk sikkerhet, er imidlertid ikke brukervennlig, fordi hvert knivskifte pga. den nødvendige sikkerhetstesten i praksis bare kan utføres av autoriserte fagforretninger og derfor bare kan utføres med forholdsvis høyt tidsforbruk og kostnad. Hovedformålet med oppfinnelsen er å skape en mer brukervennlig utforming av elektro-plenklippere. Dette søkes løst ved plenklippere av den kjente typen, ved å skaffe en anordning for feste av vingeknivene til motorakselen, som tillater veksling hos brukerene, samtidig som den elektriske sikkerheten blir opprettholdt, uten å nødvendiggjøre høyspenningstest mellom motor og kniv. A blade holder for lawnmowers, which is designed in this way with regard to electrical safety, is not user-friendly, however, because each blade change due to the required safety test in practice can only be carried out by authorized specialist shops and can therefore only be carried out with a relatively high time consumption and cost. The main purpose of the invention is to create a more user-friendly design of electric lawnmowers. This is sought to be resolved with lawnmowers of the known type, by providing a device for attaching the wing blades to the motor shaft, which allows users to switch, while electrical safety is maintained, without necessitating a high-voltage test between motor and blade.

Dette komplekse problemet kan løses ved å utforme anordningen som angitt i den karakteriserende delen av patentkrav 1. This complex problem can be solved by designing the device as indicated in the characterizing part of patent claim 1.

Ved et knivfeste av dette slaget, blir sikkerheten i samsvar med VDE-bestemmelse 0 730, del 1, paragraf 29 sikret, fordi det mellom den sentrale spennskruen og det opptilliggende området av vingekniven kan opprettholdes en minste luftspalte på 4 mm. With a knife attachment of this type, safety in accordance with VDE regulation 0 730, part 1, paragraph 29 is ensured, because a minimum air gap of 4 mm can be maintained between the central clamping screw and the adjacent area of the wing knife.

Det har vist seg særlig fordelaktig, dersom de ekstra skrueforbindelsene hver består av en hodeskrue og en mutter og hvor mutteren er innsatt henholdsvis plassert tapssikret i koblingslegemet. It has proven to be particularly advantageous if the additional screw connections each consist of a head screw and a nut and where the nut is inserted respectively placed in a loss-proof manner in the coupling body.

Det foretrekkes at festeanordningen har to ekstra skrueforbindelser radialt forskjøvet i forhold til spennskruen på koblingslegemet, fordi en dermed lett kan unngå ubalanse i knivfestet. It is preferred that the fastening device has two additional screw connections radially offset in relation to the clamping screw on the coupling body, because an imbalance in the knife attachment can thus easily be avoided.

Det har videre vist seg fordelaktig, dersom koblingslegemet til knivkoblingen danner en byggeenhet med en vifterotor for motorkjølingen og når det mellom motorakselen og koblingslegemet finnes en kontaktfast inngrepsforbindelse. I det siste tilfellet er det tilstrekkelig at den sentrale spennskruen bare sikrer koblingslegemets og/eller vifterotorens aksielle stilling på motorakselen, mens dreiemomentoverføringen blir sikret ved anlegg. It has also proven advantageous if the coupling body of the blade coupling forms a building unit with a fan rotor for the motor cooling and when there is a non-contact engagement connection between the motor shaft and the coupling body. In the latter case, it is sufficient that the central clamping screw only secures the axial position of the coupling body and/or the fan rotor on the motor shaft, while the torque transmission is secured during installation.

I figuren er det vist en elektro-plenklipper i vertikalsnitt igjennom dens bærekonstruksjon i innbyggningsområdet for elektromotoren og vingeknivene, idet detaljene ved knivkoblingen som forbinder vingeknivene med motoraksen er vist. In the figure, an electric lawnmower is shown in vertical section through its support structure in the installation area for the electric motor and the blade blades, as the details of the blade coupling which connects the blade blades with the motor shaft are shown.

Av tegningen går det fram, at en elektromotor 1 er montert med aksel 2 rettet nedover mot plenklipperens bærekonstruksjon 3. From the drawing, it appears that an electric motor 1 is mounted with shaft 2 directed downwards towards the lawnmower's support structure 3.

Fra undersida av bærekonstruksjonen 3 er det på motorakselen 2 skjøvet på et koblingslegeme 4 med sin koblingsmuffe 5. Dette koblingslegemet 4 er tilvirket av et isolermateriale, f.eks. plast, idet dens koblingsmuffe 5 inneholder en medbringer 6, som står i dreiefast inngrep med ei generelt sektorformet forløpende koblingsflate 7 på motorakselen 2. From the underside of the support structure 3, a coupling body 4 with its coupling sleeve 5 is pushed onto the motor shaft 2. This coupling body 4 is made of an insulating material, e.g. plastic, as its coupling sleeve 5 contains a driver 6, which is in rotatable engagement with a generally sector-shaped continuous coupling surface 7 on the motor shaft 2.

I ett stykke med koblingslegemet 4 er det i tillegg utformet en vifterotor 8 som griper inn i en halsformet utsparing 9 i bærekonstruksjonen 3 og som hovedsakelig brukes for å kjøle elektromotoren 1. In one piece with the coupling body 4, a fan rotor 8 is additionally formed which engages in a neck-shaped recess 9 in the support structure 3 and which is mainly used to cool the electric motor 1.

For å forbinde koblingslegemet 4 over dets koblingsmuffe 5 med motorakslen 2 tjener en sentral hodeskrue 10, som kan skrues inn i en koaksial gjengeboring 11 på motorakselen 2 og som da virker mot ei underlagsskive 12 som danner anlegg mot en endevegg 13 i koblingsmuffa 5. To connect the coupling body 4 over its coupling sleeve 5 with the motor shaft 2, a central head screw 10 is used, which can be screwed into a coaxial threaded bore 11 on the motor shaft 2 and which then acts against a washer 12 which forms an abutment against an end wall 13 in the coupling sleeve 5.

Endeveggen 13 ligger i bunnen av ei nedoverrettet utsparing 14 i koblingslegemet 4, hvilken opptar både underlagsskiva 12 og hodet på hodeskruen 10. Dybden på utsparingen 14 i spennskruens 10 akseretning er dimensjonert slik, at den fri endeflata på hodeskruens hode inntar en avstand 16 fra koblingslegemets 4 fri endeflate 15, som minst utgjør 4 mm. The end wall 13 lies at the bottom of a downwardly directed recess 14 in the coupling body 4, which occupies both the base plate 12 and the head of the head screw 10. The depth of the recess 14 in the axial direction of the tension screw 10 is dimensioned so that the free end surface of the head screw occupies a distance 16 from the coupling body 4 free end surface 15, which is at least 4 mm.

Mot den fri endeflata 15 til koblingslegemet 4 vil det sentrale midtavsnitt 17 på vingekniven 18 danne anlegg og det på en slik måte at medbringertapper 19 på koblingslegemet 4 griper passende inn i motsvarende utsparinger 20 i det sentrale midtavsnittet 17. Against the free end surface 15 of the coupling body 4, the central central section 17 of the wing blade 18 will form contact and in such a way that the driver pins 19 on the coupling body 4 engage appropriately in corresponding recesses 20 in the central central section 17.

Den løsbare forankringen 18 på koblingslegemet 4 blir oppnådd ved hjelp av to ytterligere skruforbindelser 21, som har en sideveis forskjøvet plassering i forhold til spennskruen 10 og som er avskjermet i forhold til denne ved hjelp av isolermaterialet i koblingslegemet 4. De to skruforbindelsene 21 angriper såvel på vingekniven 18 som på koblingslegemet 4 radialt utenfor medbringerutsparingen 20 og medbringertappene 19. De består hver av en hodeskrue 21 og en mutter 23 som er tapsfritt innsatt henholdsvis innpasset i koblingslegemet 4. For å veksle vingekniven 18 er det bare nødvendig å skrue hodeskruene 22 ut av mutrene 23 og etter veksling av vingekniven 18 og trekke dem til igjen. The detachable anchoring 18 on the coupling body 4 is achieved by means of two further screw connections 21, which have a laterally offset position in relation to the tension screw 10 and which are shielded in relation to this by means of the insulating material in the coupling body 4. The two screw connections 21 attack as well on the wing knife 18 as on the coupling body 4 radially outside the carrier recess 20 and the carrier pins 19. They each consist of a head screw 21 and a nut 23 which are losslessly inserted or fitted into the coupling body 4. To change the wing knife 18 it is only necessary to unscrew the head screws 22 of the nuts 23 and after changing the wing knife 18 and tighten them again.

Fordi skrueforbindelsene 21 er avskjermet mot den sentrale hodeskruen 10 av isolermaterialet i koblingslegemet 4 og dessuten den sentrale hodeskruen 10 har den forskrevne minimumsavstand 16 fra den monterte vingekniven 18, sikres forskriftsmessig elektrisk sikkerhet på enkel måte og gir samtidig brukervennlig veksling av vingekniven 18. Because the screw connections 21 are shielded from the central head screw 10 by the insulating material in the coupling body 4 and, moreover, the central head screw 10 has the prescribed minimum distance 16 from the mounted vane knife 18, electrical safety is ensured in accordance with regulations in a simple way and at the same time provides user-friendly changing of the vane knife 18.

Claims

1. Device for attaching rotating blade knives to the motor shaft of electrically powered lawnmowers, where a blade coupling can be connected or is connected to the motor shaft by means of a central clamping screw, characterized in that the tension screw (10), with its head, is engaged in a recess (14) in a coupling body consisting of insulating material, e.g. plastic, that there is a minimum distance (16) of 4 mm between the end surface of the tension screw (10) head and the free end surface (15) of the coupling body (4) or the recess, and that the wing knife (18) is anchored releasably on the end surface (15) of the coupling body (4) with at least one further screw connection (21) which has a laterally offset position in relation to the tension screw (10) and is shielded in relation to this by the material in the coupling body (4).

2. Device in accordance with patent claim 1, characterized in that the further screw connections (21) each consist of a head screw (22) and a nut (23), the nut being inserted or molded into the coupling body (4).

3. Device in accordance with one of patent claims 1 and 2, characterized in that two additional screw connections (21) are placed on the coupling body (4), radially displaced in relation to the tension screw (10).

4. Device in accordance with one of patent claims 1-3, characterized in that the coupling body (4) for the blade coupling forms a unit with a fan rotor (8) for the engine cooling.

5. Device in accordance with one of patent claims 1-4, characterized in that a rotationally secure engagement connection (6, 7) is arranged between the motor shaft (2) and the coupling body (4).