WO1991001859A1

WO1991001859A1 - Chain drive device and methods of forming same

Info

Publication number: WO1991001859A1
Application number: PCT/AU1990/000320
Authority: WO
Inventors: Cornelis Johannes Maria Beerens
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-08-04
Filing date: 1990-08-02
Publication date: 1991-02-21
Anticipated expiration: 1992-02-04

Abstract

A saw chain drive device includes a clutch drum (21) and a fixed drive sprocket (1). The clutch drum (21) comprises an end wall (22) provided with apertures (26) which are radially spaced from the axis of rotation of the saw chain drive device and are located so as to receive projections (6) extending from teeth (4) on the drive (1). The fixed drive sprocket (1) is then rotationally immovable relative to the clutch drum (21).

Description

CHAIN DRIVE DEVICE MD METHODS OF FORMING SAME

This invention relates to saw chain drive devices comprising of a clutch drum and a permanently fixed drive means for use in chain saws.

The invention relates to two forms of drive means, a fixed drive sprocket which directly drives the saw chain, and a fixed drive spline which drives the saw chain indirectly with the addition of a replaceable drive sprocket. In the first instance the drive sprocket is permanently fixed to the clutch drum and in the second instance the drive spline is permanently fixed to the clutch drum.

It is conventional in the manufacture of saw chain drive devices to fix the drive means to the clutch drum by brazing. The weakness of this construction that the torque transferred from the clutch drum to the drive means is limited by the strength and the quality of the brazed joint and the brazing material.

Accordingly, it is an object of this invention to provide a saw chain drive device comprising a clutch drum and drive means, the connection between these two parts being effected by means or methods in addition to or instead of brazing.

It is a further object of the invention to provide a method of forming a saw chain drive device comprising a clutch drum and drive means, by the provision of additional connecting means.

To this end there is provided a saw chain drive device

« comprising a clutch drum and drive means said clutch drum comprising an end wall provided with at least two apertures, with at least one of said apertures being radially spaced from the axis of rotation of said saw chain drive device, said drive means being provided with at least two projections located so as to be received in said apertures of said end wall such that said drive means is rotationally immovable relative to said clutch drum. __

There is further provided a method of forming a saw chain drive device comprising a clutch drum and drive means, said drive means being provided with at least two projections, said projections being used as a punch tool to form at least one aperature radially spaced from the the axis of rotation within the end wall of the said clutch drum.

It can be seen that the saw chain drive device of the invention relies on a mechanical connection between the drive means and the clutch drum, and can be used as a substitute or in addition to conventional brazing techniques to give added strength to the final product.

To aid εecurement of the drive means to the clutch drum the said projections may in part be deformed after insertion in the apertures of the end wall. Such deformation may be carried out with or without the assistance of heat application. As an alternative thereto, a body such as a washer, may be welded to the projections once inserted through the apertures of the end wall or welded to both the projections and the end wall of the clutch drum.

In the preferred embodiment said drive means comprises a drive sprocket with one said radially spaced projections projecting axially from each tooth of the fixed drive sprocket. In an alternative preferred empodiment, the drive means may include a flange, the projections are extended from the flange. Such a drive means may be inserted from outside or within the clutch drum.

In a preferred method of forming the saw chain drive device, the drive means and clutch drum are pressed together, the projections of the drive means being used as a punch tool to create the apertures in the end wall of the clutch drum during assembly. If desired, the drive means and the clutch drum may additionally be brazed together to give added strength to the product. While brazing might be employed as desired, it should not be regarded as being essential to the present invention. Specific examples of saw chain drive devices, comprising clutch drums and drive meanss in accordance with the present invention will now be described with reference to the accompanying drawings in which:-

Figure 1 is a perspective view of a fixed drive sprocket in accordance with this invention.

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Figure 2 is a perspective view of a clutch drum in accordance with this invention.

Figure 3 is a perspective view of a saw chain drive device in accordance to this invention comprising a clutch drum and fixed drive sprocket.

Figure 4 is an elevation view showing the inside of a clutch drum in accordance to this invention.

Figure 4a is a side view of a clutch drum in accordance to this invention.

Figure 4b is a sectional view taken along line aa of figure 4.

Figure 5 is a plan view of an alternative fixed drive sprocket in accordance to this invention.

Figure 5a is a sectional view of the fixed drive sprocket of figure 5.

Figure 6 is a plan view of an alternative fixed drive sprocket in accordance to this invention.

Figure 6a is a sectional view of the fixed drive sprocket of figure 6.

Figure 7 is a sectional view of a further embodiment of a clutch drum and a fixed drive sprocket in accordance with this invention. Figure 7a is a partial enlarged sectional view of the circled region of figure 7.

Figure 8 is a plan view of an alternative fixed drive sprocket in accordance with this invention wherein the projections are formed upon a flange extending from the sprocket, and the sprocket is inserted from within the clutch drum.

Figure 8a is a sectional view of the sprocket of figure 8 in combination with a clutch drum.

Figure 9 is a sectional view of a somewhat similar fixed drive sprocket and clutch drum of figure 8a wherein the sprocket is inserted from outside the clutch drum.

Figures 10 and 11 are sectional views similar to figures 8a and 9 showing an alternative embodiment employing a fixed drive spline as a drive means. The figures also show the placement of removable drive sprocket placed on the spline section of the fixed drive spline.

A particularly preferred embodiment of the invention will now be discussed with reference for figures 1 to 4b.

A fixed drive sprocket (1) is provided with a through bore (2), a spigot (3) and teeth (4). Said teeth (4) are provided with projections (6) which are located around the perimeter of the fixed drive sprocket (1). A clutch drum (21) has an end wall (22)'and apertures (26) located radially with respect to the axis of rotation of the clutch drum and a centrally^** located aperture (24). When formed (figures 3,4, & 4b), the projections (6) of the fixed drive sprocket (1) is received in the central aperature (24) of the end wall (22) of the clutch drum (21).

In a particularly preferred method of formation of saw chain drive devices of the invention the fixed drive sprocket (1) is used as a punch tool, the projections (6) forming the apertures (26) and the central aperture (24) acting as a guide by receiving spiggot (3) of the fixed drive sprocket.

In an alternative method, the central aperture (24) is also formed by using the fixed drive sprocket (1) as a punch tool. In this case both the spigot (3) and the projections (6) of the fixed drive sprocket (1) form the apertures (24 & 26) in the end wall of the clutch drum (21).

In a further, but less preferred method formation of the saw chain drive device of this invention, radially located apertures (26) and the central aperture (24) in the end wall (22) of the clutch drum (21) are preformed. The projections (6) and the spigot (3) of the fixed drive sprocket(1) are then pushed into the apertures (24) and (26).

In all three of the above methods of formation it is possible to additionally fix the fixed drive sprocket (1) to the clutch drum (21) by additional means.

An alternative sprocket in accordance with this invention is illustrated in figures 5 and 5a. The fixed drive sprocket (41) has a central through bore (2) and a spigot (3). The projections (46) are, however, spaced inward from the circumferential ends of the teeth (4). In this embodiment of the invention, the location of the radially located apertures (26) in the end wall (22) of the clutch drum (21) must be also suitably relocated do as to receive projections (46) of the fixed drive sprocket (41).

In a further embodiment of the invention (figure 6 & 6a) a fixed drive sprocket (61) is provided with teeth (4) and a central through bore (2). However, in this case the the spigot (63) is not round, being of large enough diameter so as to be reshaped whilst forming the teeth (4). The projections (6) may or may not be spaced inwardly from the radial ends of the teeth (4). As and addition to the simple mechanical connection between the fixed drive sprocket (1) and the clutch drum (21), it is possible to fix the fixed drive sprocket (1) to the clutch drum (21) by additional means. This is illustrated in figure 7 and 7a which show a fixed drive sprocket (1) with projections (6) received in apertures (not shown) of the clutch drum (21). The fixed drive sprocket (1) is permanently fixed to the clutch drum (21) by the permanent connection of a washer (108) to the projections (6).

In another form of the invention shown in figures 8 & 8a, the fixed drive sprocket (81) is formed with a flange (87) such that with a number of axially extending projections (86) extending from the flange (87) in the same direction as the teeth (4) and generally between the teeth (4). In this emodiment the flange (87) engages against the inner surface of the end wall (22) of the clutch drum (21) when assembled. The projections (86) engage in appropriate aperatures in the end wall (22) of the clutch drum (21) when assembled as shown in figure 8a.

Figure 9 shows a further embodiment somewhat similar to figures 8 & 8a except that in this embodiment the flange (97) engages an outer surface of the end wall (22) of the clutch drum (21). In this arrangement a number of radially spaced projections (96) extend from the flange in the opposite direction as the teeth (4) and when assembled with the drum, engage in appropriately located apertures located in the end wall (22). In this embodiment a central spigot (91) is located within a central aperture centred on the axis of rotation of the saw chain drive device.

Figures 10 and 11 illustrate further alternatinve embodiments somewhat similar to figures 8a and 9 except that in this case the drive means is a fixed drive spline (100). A removable drive sprocket (109) is shown placed on the spline connection (101). In figure 10, the fixed drive spline (100) has flange (102) on which the spline connection (101) is formed. The flange (102) engages with an outer surface of the end wall (22) of the clutch drum (21). The flange (102) has one or more and preferrably a number of projections (104) extending axially into the clutch drum (21) to engage in appropriate apertures in the end wall (22). A central spigot (105) engages in a central aperture of the end wall (22) and the removable drive sprocket (109) may be slid on or of the spline connection (101) as desired.

Figure 11 illustrates a similar arrangement to figure 10, except that the flange (106) on which spline connection (101) is formed_/ engages an inner surface of the end wall (22) of the clutch drum (21). In this arrangement the spline connection (101) is pushed through an central aperture in the end wall (22) whilst projections (108) are engaged in appropriate apertures in the end wall (22).

It will of course be appreciated that modifications of the present invention within the scope of the accompanying claims are envisaged to the present invention. For example it is not seen to be essential that the fixed drive sprocket (1) or the fixed drive spj.ine (100) should necessarily have a central spigot that is engaged within a central aperture of the end wall (22) of the clutch drum (21).

It can be seen that the saw chain drive device according to the invention is formed without the essentiallity of fixation of the the drive means to the clutch drum by brazing. The number of apertures through which the drive means projections are received give to the saw chain drive device added strength. Substitution of the need to braze the two pieces together allows many variations on the methods of manufacturing a saw chain drive device. The device and the method of the present invention provide significant advantages over saw chain drive device and methods of manufacture.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS;

1. A saw chain drive device comprising a clutch drum and drive means, said clutch drum comprising and end wall provided with at least two apertures with at least one of said apertures being radially spaced from the axis of rotation of said saw chain drive device, said drive means being provide with at least two axially extending projections located so as to be received in said apertures of said end wall.

2. A saw chain drive device as claimed in claim 1 with said

_ drive means having a centrally located spigot and said clutch drum having a centrally located aperture, sized to receive said spigot.

3. A saw chain drive device as claimed in either claim 1 or claim 2 wherein said drive means is a fixed drive sprocket with radially extending teeth.

4. A saw chain drive device as claimed in either claim 1 or claim 2 wherein said drive means is a fixed drive spline.

5. A saw chain drive device as claimed in claim 3 wherein at least one of said projections extend axially from one or more said radially extending teeth of said fixed drive sprocket.

6. A saw chain drive device as claimed in claim 5 wherein at least one of said projections are located at a distal end of said radially extending teeth.

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7. A saw chain drive device as claimed in claim 5 wherein at least one of said projections are spaced inwardly from the distal end of said radially extending teeth.

8. A saw chain drive device as claimed in either of claims 1 to 4, wherein said drive means includes a flange region adapted to abut an inner or outer surface of the end wall of said clutch drum.

9. A saw chain drive device as claimed in either of claims 1 to 8, wherein said drive means is additionally secured to said clutch drum by an additional bonding material.

10. A method of manufacturing a saw chain drive device as claimed in either of claims 1 to 9, wherein said drive means is used as a punch tool to form said at least one aperture in said end wall of said clutch drum.

11. A method of manufacturing a saw chain drive device as claimed in claim 10, wherein all said apertures are formed by using said drive means as a punch tool.

12. The steps and features disclosed herein or any combinations thereof.