GB2369982A

GB2369982A - Trimmer thread feed mechanism

Info

Publication number: GB2369982A
Application number: GB0128516A
Authority: GB
Inventors: Zhibin Yang; Zhiqiang Lu; Bangyan Qi
Original assignee: SUZHOU TAIHU IND CO Ltd
Current assignee: SUZHOU TAIHU IND CO Ltd
Priority date: 2000-12-04
Filing date: 2001-11-29
Publication date: 2002-06-19
Anticipated expiration: 2021-11-29
Also published as: CN2459863Y; DE20119651U1; FR2817706B1; FR2817706A1; NL1019458C2; GB0128516D0; GB2369982B

Abstract

An automatic cutting-thread feed apparatus of lawnmower or trimmer comprising an thread case (2 figure 2) connected with an output shaft 1 a thread reel 3 in the thread case 2, a cutting thread 13 reeled on the thread reel 3, a ratchet wheel 4 with a plurality of ratchets (5 figure 2) disposed on the thread reel 3, a stop block 6 pressing on one of these ratchets 5, a backup plate 7 disposed on the stop block 6. The backup plate 7 and a spring 9 are fitted over a core pin 8. The core pin 8 is fixed on the thread case 2 along a radial direction. The spring 9 is to push the stop block 6 to press on the ratchet 5. Above all, it is able to feed out cutting thread automatically after abrasion shortens the cutting thread, to keep proper working length of cutting thread and to make lawnmower at its best state all the time.

Description

Automatic Cutting-thread Outstretching Apparatus of Lawnmower FIELD OF THE

INVENTION

The present invention relates to a lawnmower, particularly to an automatic cutting-thread outstretching apparatus of a lawnmower.

BACKGROUND OF THE INVENTION

Lawnmower, as common electric tool, is mainly used to prune lawn. Its working head generally includes two parts, one includes an electric machine and the other includes a mowing device. The mowing device has two types: cutter wheel type and thread box type. The former cuts lawn by means of blades, while the latter utilizes the cutting force generated by the high-speed rotation of a cutting thread to cut lawn. Both types of lawnmowers will be abraded after having been used for a period of time. For the cutter wheel type lawntnower, the abraded blades should be replaced. For the thread box type of lawn nower, due to the abrasion will shorten the effective length of the cutting thread, as a result, the cutting thread cannot work effectively until it is replaced by the one stretched out from thread wheel. In addition, the abrasion of cutting thread is faster than that of blades. Therefore, it is necessary for an operator to extend cutting thread frequently during using the lawnmower to make sure the cutting thread having enough working length and to maintain the best working state of the lawnmower. This brings a lot of extra work to the operator.

OBJECTS OF THE INVENTION

The objectives of the present invention are to overcome the shortcomings of the prior art lawnmowers and to provide an automatic cutting-thread

outstretching apparatus of a lawnmower. The apparatus of the present invention is able to stretch out the cutting thread automatically after abrasion of the cutting thread to keep proper working length of the cutting thread and to make the la vnmower at its best working state all the time.

SUMMARY OF THE INVENTION

The present invention provides an automatic cutting-thread outstretching apparatus of lawnmower. The apparatus of the present invention comprises a thread case connected with an output shaft, a thread reel disposed in the thread case, a cutting thread reeled on the thread reel, a ratchet wheel disposed on the thread reel, a plurality of ratchets disposed on the ratchet wheel, a stop block pressing-disposed on one of the ratchets, a backup plate disposed on the stop block, a core pin, and a spring disposed on the core pin. Wherein, the core pin is slipped into the backup plate, one end of the bowel pin is fixed on the thread case along diameter direction, and the spring presses the stop block against the ratchet.

The present invention further provides an automatic cutting-thread outstretching apparatus of lawnmower. The apparatus of the present invention

comprises a thread case connected with an output shaft, a thread reel disposed in the thread case, a ratchet wheel on the thread reel, a plurality of ratchets disposed on the ratchet wheel, a stop block pressing-disposed on one of the ratchets, a backup plate disposed on the stop block, a core pin and a spring fitted over the core pin, wherein, the core pin is fixed on the thread case along diameter direction, and the spring presses the stop block against the ratchet. A core pin hole is disposed on the outwall of the thread case along diameter direction. The core pin is a bolt shaped pin and is mounted on the thread case with screw through the core pin hole. The stop block is positioned in the thread case, and the backup plate on the stop block is fitted over the core pin through a guiding hole at the top of thread case. On the inwall of thread case, there is a guiding bar beside the stop block. The present invention uses the stop block ant the ratchet wheel to connect or disconnect the thread reel and the thread case. The stop block, under the action of the spring and the centrifugal force, moves along the diameter direction in the guiding hole of the thread case. When the stop block locks one ratchet on the thread reel, it will bring the thread reel to rotate with the thread case together; when it leaves the ratchet, the thread reel will rotate freely, relative to the thread case.

The automatic cutting-thread outstretching apparatus of a lawnmower of the present invention has following advantages: 1. When abrasion shortens the effective length of the cutting thread,

the cutting resistance will reduce so that the rotation of the electric machine will be speeded up, and thus the centrifugal force will increase. Then, the stop block, because of the stronger centrifugal force, overcomes elastic force of the spring to leave the ratchet. Meanwhile, the thread reel is driven by centrifugal force of cutting thread to turn over a ratchet automatically so as to stretch out the cutting thread. After that, the cutting resistance increases and the rotary speed of the electric machine slows down, so that the centrifugal force acting on the stop block is less than the elastic force of spring. At last, the stop block presses on next ratchet.

2. The automatic cutting-thread outstretching apparatus of lawnmower of the present invention has simple structure and convenient operation. Above all, it is able to stretch out cutting thread automatically, to keep proper working length of cutting thread and to make lawnmower at its best state all the time.

Brief Explanation of Drawings Figure 1 is the front view of the automatic cutting-thread outstretching apparatus of lawomower of the present invention.

Figure 2 is the top view of the automatic cutting-thread outstretching apparatus of lawnmower of the present invention.

Figure 3 is the enlarged drawing of section A in figure 1.

Figure 4, figure 5 and figure 6 are working state drawing of the present

invention. In the drawings, 1 represents output shaft, 2 represents thread case, 3 represents thread reel, 4 represents ratchet wheel, S represents ratchet, 6 represents stop block, 7 represents backup plate, 8 represents core pin, 9 represents spring, 10 represents core pin hole, l l represents guiding hole, 12 represents guiding bar, and 13 represents cutting thread.

Preferred Embodiment The automatic cutting-thread outstretching apparatus of lawnrnower of the present invention is further described and explained as follows in combination of drawings. Figure 1 and figure 2 show the automatic cutting-thread outstretching apparatus of lawnrnower of the present invention. As shown by Figure 1 and Figure 2, the automatic cutting-thread outstretching apparatus of lawnmower of the present invention comprises a thread case 2 connected with an output shaft 1, a thread reel 3 disposed in the thread case 2, a plurality of rolls of thread 13A reeled on the thread reel 3, and the ends of the thread extended out from the thread case 2 to form cutting thread 13, a ratchet wheel 4 disposed on the thread reel 3, a plurality of ratchets S disposed on the ratchet wheel 4, a stop block 6 pressing-disposed on one of the ratchets 5, a backup plate 7 disposed against the stop block 6, a core pin 8 (Figure 3) over which the backup plate 7 and a spring 9 are fitted, and a piece of cutting thread s

13. When the stop block 6 locks the ratchet 5, the thread reel 3 will integrate with the thread case 2. Please refer to Figure 3, one end of the core pin 8 is fixed on the thread case 2 along the diameter direction, and the spring 9 is to push the backup plate 7 to make the stop block 6 press on the ratchet 5. A core pin hole 10 is disposed on the wall of the mentioned thread case 2 along the diameter direction. The core pin 8 is a bolt shaped pin and is mounted on the thread case 2 with screw 8A through the core pin hole 10. The backup plate 7 on the stop block 6 is fitted over the core pin 8 through a guiding hole 11 at the top of the thread case 2. On the inwall of thread case 2, a guiding bar 12 is disposed beside the stop block 6. The stop block 6, under the action of the spring 9 and centrifugal force F. moves along the guiding hole 11 and the guiding bar 12 in diameter direction.

The present invention uses the stop block 6 and the ratchet wheel 4 to connect or disconnect the thread reel 3 and the thread case 2. The stop block 6, under the action of the spring 9 and centrifugal force, moves along diameter direction in the guiding hole 11 in the thread case 2. When the stop block 6 locks one ratchet 5, the thread case 2 is connected together with the thread reel 3 and the thread reel 3 will rotate together with the thread case 3. When the stop block 6 leaves the ratchet 5, the thread reel 3 will be driven by the centrifugal force of the cutting thread 13 and rotate freely relative to the thread case 2. In this way, the cutting thread 13 will be extended to a proper length.

Figure 4, Figure 5 and Figure 6 show the working state of the automatic cutting-thread outstretching apparatus of lawnmower of the present invention. As shown by Figure 4, the lawnmower tDS along the direction B. When abrasion shortens the cutting thread 13, the cutting resistance will reduce so that the rotation of the output shaft 1 will be speeded up, and thus the centrifugal force will increase.

Then, the stop block 6, because of the stronger centrifugal force F. overcomes the elastic force of the spring 9 to move towards centrifugal direction. As shown by Figure 5, when the stop block 6 still moves towards centrifugal direction, the stop block 6 will leave the ratchet 5. Meanwhile, the thread reel 3 is driven by centrifugal force of the cutting thread 13 to turn over a ratchet along direction C, relative to the thread case 2, so as to stretch out the cutting thread 13. After that, as shown by Figure 6, the cutting resistance increases and the rotation speed of the output shaft 1 slows down, so that the centrifugal force acting on the stop block 6 is less than the elastic force of the spring 9. At last, the stop block 6 moves towards centripetal direction and presses on next ratchet 5. The present invention has simple structure and convenient operation. Above all, it is able to stretch out the cutting thread automatically, to keep proper working length of the cutting thread and to make the lawnmower at its best working state all the time.

Claims

1. An automatic cutting-thread outstretching apparatus of a lawnmower, comprising an thread case [2] connected with an output shaft [1], an thread reel [3] in the thread case [2], a cutting thread [13] reeled on the thread reel [3], characterized in that: a ratchet wheel [4] with a plurality of ratchets [5] is disposed on the thread reel [3], a stop block [6] is pressing-disposed on one of the ratchets [5], a backup plate [7] is disposed on the stop block [6], the backup plate [7] and a spring [9] are fitted over a core pin [8], the core pin [8] is fixed on the thread case [2] along diameter direction, and the spring [9]presses the stop block [6] against the ratchet [5].

2. The automatic cutting-thread outstretching apparatus of a lawnmower in accordance with claim l, characterized in that: a core pin hole [ l O] is disposed on the thread case [2] along diameter direction, the core pin [8] is a bolt shaped pin and is mounted on the thread case [2] with screw through the core pin hole [10], the stop block [6] is disposed in the thread case [2], the backup plate [7] on the stop block [6] is fitted over the core pin [8] through a guiding hole [11] at the top of the thread case [2], a guiding bar [12] is disposed on the inwall of the thread case [2] beside the stop block [6].