ZA200905284B

ZA200905284B - Pneumatic powered rotary tool

Info

Publication number: ZA200905284B
Application number: ZA200905284A
Authority: ZA
Inventors: Bernard Lionel Gien
Original assignee: Gien Bernard L
Priority date: 2008-05-28
Filing date: 2009-07-29
Publication date: 2010-07-28

Description

PNEUMATIC POWERED ROTARY TOOL

FIELD OF THE INVENTION

This invention relates to rotary tools, which are pneumatically powered and more particularly to tools which are hand held.

One kind of tool that is well known is the hand held grinder which has a pair of oppositely disposed laterally extending handles. These grinders are frequently powered by rotary motors having eccentric stators. The motors are effective and can sometimes operate at speeds in excess of 15000 rpm. The rotor runs in the eccentric stator and a power shaft extends co-axially with the rotor. Where the tool is a grinder it is essential that a water supply be applied to the grinding tip to cool the tip during use and also to flush the ground material from the working interface.

The flushing water is introduced through passages connecting a water supply directly to the operatively upper end of the rotor shaft, which is commonly supported by an upper bearing at its upper end. This gives rise to maintenance problems owing to damage to this upper bearing as a result of the ingress of water into the bearing.

, . .

Another common problem with this kind of tool is the sealing of the inlet passages and the exhaust passages from each other to separate inlet air from exhaust air. This sealing in known motors is effected either across the top of the rotor providing an air inlet flow parallel to the rotor axis and a radial exhaust flow.

Alternatively, the sealing is provided along the length of the rotor parallel to the axis of the rotor. This allows oppositely disposed radial inlet and outlet passages to be used. Both these kinds of air flow passages give rise to complications in the manufacture of the motor of the tool.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a simplified air motor for use in tools of the kind referred to in which the above disadvantages are at least appreciably mitigated.

SUMMARY OF THE INVENTION

According to this invention there is provided a pneumatic powered rotary tool including: a body housing a rotor mounted eccentrically within a stator for rotation therein; manipulating handles on opposite sides of the body, a first of which has an air supply passage to supply air to the rotor, and a second of which has an exhaust passage for expelling exhaust air from the rotor; an axial extension to the body at one end thereof, the extension providing a housing for a rotor power take-off shaft and its supporting bearings; and a power take-off shaft rotatably fast with the rotor and having an axial water supply passage therethrough.

The stator may be mounted within the body to provide axially spaced chambers in the body, the chambers being sealed from each other and forming separated inlet and outlet air chambers opening into the interior of the stator, the inlet chamber being in communication with the air supply passage and the outlet chamber being in communication with the exhaust passage.

A circumferential seal may be mounted on the stator to seal against an inner wall of the body of the rotary tool, thereby providing the axially spaced chambers within the body.

The rotary tool may have a water supply passage in communication with the axial water supply passage of the power take-off shaft for the supply of water to the water supply passage of the power take-off shaft. Then, the water supply passage may be defined within one of the handles of the tool.

The rotary tool may include a stop valve for controlling the flow of air to the rotor, the stop valve being mounted in the first handle and biased to a closed position and a hand operated lever pivotally mounted on the handle for opening the valve against its bias.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will become apparent from the following description of one example of a pneumatic powered rotary tool according to this invention.

In the accompanying drawings

Figure 1 shows a partly sectioned bottom plan view of a pneumatic powered rotary tool in accordance with the invention;

Figure 2 shows a sectional side view of the pneumatic powered rotary tool through a section II-1l In Figure 1;

Figure 3 shows a sectional view of the pneumatic powered rotary tool through a section II-ll In Figure 1;

Figure 4 shows a partial sectional view top plan view of the pneumatic powered rotary tool through a section IV-IV In Figure 2;

Figure 5 shows a partial sectional view top plan view of the pneumatic powered rotary tool through a section V-V In Figure 2;

Figure 6 shows a partial perspective view from above, of the body and stator of the pneumatic powered rotary tool with the rotor removed; and

Figure 7 shows an exploded perspective view of the axial extension and rotor, stator and body with handles of the pneumatic powered rotary tool.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings, a pneumatic powered rotary tool in accordance with the invention is generally indicated by reference numeral (1). The rotary tool (1) comprises a bit grinder.

The bit grinder (1) consists of a body (2) housing a stator (3) in which a rotor (4) is mounted eccentrically within a cylindrical cavity (33) defined by the stator (3) for rotation within the stator (3). The rotor (4) has four angularly spaced, radially movable blades (5), shown clearly in Figures 1, 4 and 5. The blades (5) are received within radial slots (34) defined in the rotor (4). Such a configuration of radially movable blades received within slots in a rotor are common to this kind of pneumatic powered rotary tool and the operation of these blades will not be described further.

A pair of manipulating handles (35,12) is attached to the body (2), on opposed sides thereof.

The body (2) defines a cylindrical cavity (36) and supports the stator (3), which is mounted eccentrically therewithin. A circumferential seal (6) mounted in a ring (7) extends outwardly from the stator (3) and seals against the inner wall (37) of the body (2). The seal (6) widens gradually from its narrowest to its widest width, as shown clearly in Figures 1, 3, 4 and 5, thereby providing for the stator (3) to be mounted eccentrically within the body cavity (36). This seal (6) divides the body cavity (36) into two axially separated compartments (8) and (9).

The upper compartment (8) forms an inlet chamber and has an inlet port (38) through which air under pressure is received from a compressor (not shown) that is connected to the rotary tool (1), as indicated by the arrows (39). An outlet port (40) for the inlet chamber (8) provides an air inlet to the stator cavity (33) and thus to the rotor (4).

The lower compartment (9) forms an outlet chamber and an inlet port (41) leads from the stator cavity (33) to the outlet chamber (9). An exhaust port (10) is defined through the body wall at (11) from which energy-exhausted air may

CT , E2009/05z84 escape via the hollow handle (12) of the rotary tool (1) to atmosphere, as indicated by the arrow (45).

An air supply passage (13) is defined through the handle (35) for the supply of compressed air to the rotor (4). The air supply passage (13) is in fluid communication with the inlet chamber (8) via the inlet chamber inlet port (38).

A stop valve (14) is provided so that the grinder operator may easily control the air supply to the rotor (4). The valve (14) has a poppet (15) slidable in a bore (42) provided in the handle (35) to seat on a tapered valve seat (16) under the bias of a compression spring (17). The valve poppet (15) provides a further tapered surface (18) to co-operate with a plunger (19) operable through a cranked lever (20).

The biasing of the valve (14) to the closed position also biases the plunger (19) to its inoperative position.

The cranked lever (20) also provides a handgrip which can be gripped by an operator holding the grinder by both handles (35,12). Air is supplied through a flexible hose (not shown) in the manner common for this type of tool and a free end of the hose is connected to the handle (35) by means of a hose fitting (48).

The rotor body (2) has an axial extension (21) enclosing and supporting a power take-off shaft (22) for the grinder. This axial extension (21) carries a bearing (23) at each end of the shaft (22) and by locating the bearings (23) in this way the water supply to the bit, described below, does not interfere with the proper operation of the grinder (1), as happens with existing tools of this kind.

The bearings (23) are held in proper spaced relationship by means of a spacer (24).

The power take-off shaft (22) is in the form of a hollow spindle (25), which defines a passageway (46) therethrough. A free outer end of the spindle carries a chuck nut (26) to hold the shank of a grinding tip (27). The grinding tip also has a bore (28).

Proceeding in an upstream direction, the water supply for the grinding tip (27) extends upwardly from the tip (27) through the passageway (46) of the spindle (25) to a lateral passage (43), which communicates with a water passage (29). A water hose fitting (49) is attached at an open end of the water passage (29). The flow of water to the grinding tip (27) is controlled by a valve assembly, indicated at (30), in the form of a tap, which, when turned, either brings the lateral passage (43) into communication with the water passage (29), or breaks the communication between these passages.

Water seals are provided as shown at (31) to prevent any ingress of water or other materials into the stator (3). It will be appreciated that the bearings (23) are separated from the water supply and cannot suffer contamination from the water supply or from the ingress of any material entrained in the water supply. A muffler (32) can be provided in the free exhaust end (44) of the handle (12) to prevent undue noise when the grinder (1) is operated.

From the above description it will be appreciated that the grinder is of simpler construction than those presently available, avoids problems associated with bearing positions in the path of cooling water for the tool and affords a direct flow of air to the rotor.

It will further be appreciated that modifications to the specific embodiment of the invention described can be made without departing from the scope of the invention.

Claims

Cli oc —_— CLAIMS

1. A pneumatic powered rotary tool including: a body housing a rotor mounted eccentrically within a stator for rotation therein; manipulating handles on opposite sides of the body, a first of which has an air supply passage to supply air to the rotor, and a second of which has an exhaust passage for expelling exhaust air from the rotor; an axial extension to the body at one end thereof, the extension providing a housing for a rotor power take-off shaft and its supporting bearings; and a power take-off shaft rotatably fast with the rotor and having an axial water supply passage therethrough.

2. The rotary tool as claimed in claim 1, in which the stator is mounted within the body to provide axially spaced chambers in the body, the chambers being sealed from each other and forming separated inlet and outlet air chambers opening into the interior of the stator, the inlet chamber being in communication with the air supply passage and the outlet chamber being in communication with the exhaust passage.

3. The rotary tool as claimed in claim 2, in which a circumferential seal is mounted on the stator to seal against an inner wall of the body of the rotary tool, thereby providing the axially spaced chambers within the body.

4. The rotary tool as claimed in claim 1 which has a water supply passage in communication with the axial water supply passage of the power take-off shaft for the supply of water to the water supply passage of the power take- off shaft.

5. The rotary tool as claimed in claim 4, in which the water supply passage is defined within one of the handles of the tool.

6. The rotary tool as claimed in claim 1, which includes a stop valve for _ controlling the flow of air to the rotor, the stop valve being mounted in the first handle and biased to a closed position and a hand operated lever’ pivotally mounted on the handle for opening the valve against its bias.

7. A pneumatic powered rotary tool substantially as herein described and illustrated with reference to the accompanying diagrammatic drawings. DATED THIS 29" DAY OF JULY 2009. FOR THE’ NT (JOHN & KERNICK) FOR THE APPLICANT